Patent Application
20050004494
This invention relates to lancing devices and methods for obtaining samples of blood and body fluids for analysis.
Many medical procedures in use today require a relatively small sample of a body fluid, such as blood or interstitial fluid, in the range of less than 50 μL. It is more cost effective and less traumatic to the patient to obtain such a sample by lancing or piercing the skin at a selected location, such as the finger or forearm, to enable the collection of 1 or 2 drops of blood, than by using a phlebotomist to draw a tube of venous blood. With the advent of home use tests for the self monitoring of blood glucose, there is a requirement for a simple procedure which can be performed in any setting without a person needing the assistance of a professional.
Lancets in conventional use generally have a rigid body and a sterile needle which protrudes from one end. The lancet may be used to pierce the skin, thereby enabling the expression of a blood sample. When a capillary tube or test strip is placed adjacent the expressed blood, the fluid can be collected. By a capillary tube fluid is then transferred to a test device, such as a paper testing strip. Blood is most commonly taken from the fingertips, where the supply is generally more accessible. However, the nerve density in this region causes significant pain in many patients. Sampling of alternative sites, such as earlobes and limbs, is sometimes practiced to lessen the pain. However, these sites are also less likely to provide sufficient blood samples and can make blood transfer directly to test devices more difficult. Additionally, it is often difficult for a user to determine whether a sufficiently large drop of body fluid has been expressed at the incision point to provide a sufficient sample.
Prior methods of acquiring a blood sample have suffered from the need to use two components and the resulting time lapse between the lancing action and placement of the capillary tube adjacent the lanced location, potentially allowing contamination or not collecting the fluid expressed from the body. One prior method for addressing this concern was to create a larger opening and/or to force excess fluid from the body. While this assisted in ensuring an adequate fluid supply, it potentially created a large opening to be healed and could cause the patient additional pain. Moreover, use of this method requires precise steps where the lancet is removed and the capillary tube or test strip is then correctly aligned with the lanced location. It is important for correct collection that no gap or movement of the capillary tube relative to the lanced location occur during collection. There is a need for a system to assist in removal of the lancet and placement of the capillary member with a minimum of time and movement. Further, there is a need for a compact, simple system to obtain the desired sample size without the need for excess lancing of tissue, extra pain to the patient or expressing an excess volume of body fluid.
To reduce the anxiety of piercing the skin and the associated pain, many spring loaded devices have been developed. The following two patents are representative of the devices which were developed in the 1980's for use with home diagnostic test products.
U.S. Pat. No. 4,503,856, Cornell et al., describes a spring loaded lancet injector. The reusable device interfaces with a disposable lancet. The lancet holder may be latched in a retracted position. When the user contacts a release, a spring causes the lancet to pierce the skin at high speed and then retract. The speed is important to reduce the pain associated with the puncture.
Levin et al., U.S. Pat. No. 4,517,978 describes a blood sampling instrument. This device, which is also spring loaded, uses a standard disposable lancet. The design enables easy and accurate positioning against a fingertip so the impact site can be readily determined. After the lancet pierces the skin, a bounce back spring retracts the lancet to a safe position within the device.
In home settings it is often desirable to collect a sample in order to enable a user to perform a test at home such as glucose monitoring. Some blood glucose monitoring systems, for example, require that the blood sample be applied to a test device which is in contact with a test instrument. In such situations, bringing the finger to the test device poses some risk of contamination of the sample with a previous sample that may not have been properly cleaned from the device.
Glucose monitoring devices utilize blood samples in many ways, though the two most common methods are a paper strip and a capillary tube. Monitors that utilize a paper strip require the patient to pierce a finger or appropriate location, withdraw a small sample of blood from the piercing, such as by squeezing, and then place the paper strip over the blood sample and wait until the paper strip absorbs the blood. Monitors that utilize a capillary tube require the patient to follow the process described above, except that a paper strip is not utilized to collect the blood from the skin. Instead, a small capillary tube is placed over the sample until a sufficient amount of blood is withdrawn into the capillary tube, which is then tested.
In some instances patients are diabetic, that is they are unable to properly metabolize glucose. In order to regulate insulin levels within their bodies, individuals who are diabetic must inject themselves with an appropriate amount of insulin. To determine the proper amount of insulin, an individual first must test their blood glucose levels. Typically, a patient has to ‘prick’ a fingertip with a lancet to create an incision through which blood can be withdrawn and placed on a glucose monitoring strip which then reacts and changes colors indicating the glucose level.
Haynes U.S. Pat. No. 4,920,977 describes a blood collection assembly with a lancet and micro-collection tube. This device incorporates a lancet and collection container in a single device. The lancing and collection are two separate activities, but the device is a convenient single disposable unit for situations when sample collection prior to use is desirable. Similar devices are disclosed in Sarrine U.S. Pat. No. 4,360,016 and O'Brian U.S. Pat. No. 4,924,879.
Jordan et al., U.S. Pat. No. 4,850,973 and U.S. Pat. No. 4,858,607 disclose a combination device which may alternatively be used as a syringe-type injection device or a lancing device with disposable solid needle lancet, depending on its configuration.
Lange et al., U.S. Pat. No. 5,318,584 describes a blood lancet device for withdrawing blood for diagnostic purposes. This invention uses a rotary/sliding transmission system to reduce the pain of lancing. The puncture depth is easily and precisely adjustable by the user.
Suzuki et al., U.S. Pat. No. 5,368,047, Dombrowski U.S. Pat. No. 4,654,513 and Ishibashi et al., U.S. Pat. No. 5,320,607 each describe suction-type blood samplers. These devices develop suction between the lancing site and the end of the device with the lancet holding mechanism withdrawing after piercing the skin. A flexible gasket around the end of the device helps seal the device end around the puncture site until an adequate sample is withdrawn from the puncture site or the user pulls the device away.
Garcia et al., U.S. Pat. No. 4,637,403 discloses a combination lancing and blood collection device which uses a capillary action passage to conduct body fluid to a separate test strip in the form of a micro-porous membrane. It is necessary to achieve a precise positioning of the upper end of the capillary passage with respect to the membrane in order to ensure that the body fluid from the passage is transferred to the membrane. If an appreciable gap exists therebetween, no transfer may occur. Also, the diameter of the capillary passage is relatively small, so the width of a sample transferred to the membrane may be too small to be measured by on-site measuring devices such as an optical measuring system or an electrochemical meter.
Single use devices have also been developed for single use tests, i.e. home cholesterol testing, and for institutional use, to eliminate the risk of cross-patient contamination with multi-patient use. Crosman et al., U.S. Pat. No. 4,869,249, and Swierczek U.S. Pat. No. 5,402,798, describe disposable, single use lancing devices.
The disclosures of the above patents are incorporated herein by reference.
An object of the present invention is to provide a disposable lancet unit that may be deployed easily and without causing undue pain.
Another object of the present invention is to provide a one-step system for sampling a body fluid for testing.
Another object of the present invention is to provide an apparatus that withdraws a blood sample and provides an individual with a blood glucose level reading.
A further object of the present invention is to provide an apparatus that does not require the user to perform multiple steps in order to produce a blood glucose level reading.
A further object of the present invention is to provide a lancet unit having capillary functions.
Further objects, features and advantages of the present invention shall become apparent from the detailed drawings and descriptions provided herein.
The present invention provides a device in the preferred embodiments which combines a lancing element with a capillary member to integrate in a single unit the lancing of a person's skin and the acquisition of the body fluid producing by lancing. The invention employs a lancing element which extends within the capillary member, and the body fluid passes through the capillary member in the space between the lancing element and the interior wall of the capillary.
One aspect of the present invention relates to a sampling device for sampling body fluid. The device includes a lancet, a main body and a carrier device for displacing the lancet. The device defines an annular space disposed about the lancet whereby body fluid is drawn into the annular space through capillary action. In one embodiment, the system further comprises a test strip with a reagent. In one approach, the test strip is in fluid communication with a distal end of the annular space. In another approach, the test strip is disposed within the annular space between the lancet and the main body. In one preferred embodiment, the test strip comprises a micro porous membrane.
In another embodiment the sampling device includes a main body, a lancet, a carrier for the lancet, and at least one channel disposed within the lancet to support a test strip. In this embodiment, the body fluid contacts the test strip as the annular space is filled.
In another embodiment, the sampling system includes a main body, a lancet, a carrier for the lancet and a testing device. The lancet is disposed within the main body, thereby creating an annular space between the lancet and the main body, and is advanced and retracted to allow the main body to fill with fluid. The main body is moved to or connected to a testing device for optical or electrochemical testing of the fluid.
In a still further embodiment, the sampling system includes a disposable cartridge mounted to a base unit. The base unit includes actuating structure for activating the lancet within the capillary member. Preferably the base unit may be reused and minimizes the materials and structure in the cartridge.
The present invention also relates to a method of sampling body fluid which comprises the steps of positioning the testing device over a testing site, activating the lancet carrying device, whereby the lancet forms a small incision in the testing site through which body fluid flows, drawing the body fluid into the main body of the device to contact a testing strip or sensors, to provide a user with the results.
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated 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, such alterations, modifications, and further applications of the principles of the invention being contemplated as would normally occur to one skilled in the art to which the invention relates.
The present invention provides a device and method for obtaining small volume samples of a body fluid. In preferred embodiments the invention combines a lancing element integrated with a capillary member in a single unit for lancing a person's skin and acquiring the body fluid producing by the lancing. The invention employs a lancing element which extends within the capillary member, and the body fluid passes through the capillary member in the space between the lancing element and the interior wall of the capillary member. This integrated unit is useful by itself or in combination with other devices which perform complementary functions such as promoting the expression of the body fluid from the incision, collecting and analyzing or testing the fluid. The device may be a reusable or disposable unit.
In contrast to the prior art, the present invention locates the lancet within the capillary such that the capillary is in position, and centered, over the incision before the lancet is extended to create the incision. This avoids the need for moving the capillary after the incision is made, and consequently reduces the significant difficulties that can be encountered in moving a capillary tube quickly and accurately to the site of an incision. It therefore enhances the ability to acquire the expressed body fluid without loss, delay or contamination.
In view of these purposes and advantages, it will be appreciated by those skilled in the art that the particular mechanisms used to extend and retract the lancet, and to hold the capillary tube, are not critical to the invention, although certain advantages are obtained with given embodiments, as hereafter described. Therefore, the underlying concept forming the basis for the present invention is useful with a wide variety of lancing mechanisms, as are known in the art. For example, the present invention is useful in combination with the mechanisms for extending and retracting lancets relative to a housing described, for example in application PCT/EP01/12527 and U.S. application Ser. No. 09/963,967, incorporated herein by reference. The foregoing disclosures constitute a part of the description of the present invention and its available design alternatives.
The present invention is useful with various body fluids. For example, the unit is suitable for accessing either blood or interstitial body fluid. The device may be readily configured for either fluid by controlling the distance by which the lancing member extends into the user's skin when in the extended position. For example, a depth of 0.5 to 2.5 mm will typically produce blood.
In one preferred embodiment, illustrated in
Referring to
For purposes herein, the term annular space is to be understood as encompassing generally the space between the capillary member and the contained lancet, including the variety of physical shapes that the space between the lancet and the capillary member may assume, depending at least in part on the noted possible variations. In certain preferred embodiments, the annular space 130 between lancet 120 and main body 105 is between 10 and 500 μm, and is preferably between 20 and 200 μm to obtain optimal capillary fill time with blood.
Referring now to
In addition, the flow of fluid may be enhanced by forming the lancing member and/or the interior surface of the capillary member from a material which is hydrophilic, which has been treated to be hydrophilic, or which has been coated with a hydrophilic material such as a surfactant or hydrophilic polymers. The surfaces can also be treated using polyamides, oxidation (e.g. corona/plasma treatment); plasma chemical vapor deposition; vacuum vapor deposition of metals, metaloxides or non-metaloxides; or deposition of an element which oxidizes with water. The annular space is therefore sized to provide the desired flow by capillary action with the various influences being taken into account.
Optionally an absorbent pad may be placed between the test strip and the distal end of the capillary passage for wicking body fluid from the annular space to the test strip. In the embodiment where the test strip is disposed within the annular space, no absorbent pad may be needed because the test strip will be in direct contact with the body fluid.
The lancing element or lancet 120 is received and longitudinally movable within the capillary space 130 of unit 100 between a first, retracted position, and a second, extended position. Means are provided for resiliently extending and retracting the lancet in order to make a desired incision and to then withdraw the lancet back into a shielded position.
Various means for extending a lancet relative to a housing are known in the art, and are useful in combination with the present invention. These devices, for example, typically include lancets held by carriers that are spring loaded for movement relative to the surrounding housing. Alternatively, a spring-loaded hammer may be use to impact the lancet carrier in order to drive it in the direction to lance the skin. Examples of such mechanisms are contained in the following U.S. Pat. Nos. 5,951,492; 5,857,983 and 5,964,718. The foregoing disclosures are incorporated herein by reference, and constitute a part of the description of the present invention and its available design alternatives.
These devices typically extend the lancet to a defined extent, such as by moving the lancet to a stop. Such devices frequently are produced with a predefined limit of travel for the lancet, thereby defining a penetration for the lancet into the skin. Alternatively, devices are well known which permit the user to adjust the penetration depth, such as by turning a wheel or other mechanism, with such adjustable devices frequently including a dial or other display which indicates the selected depth. These types of mechanisms are useful in combination with the present invention.
Various means may similarly be employed for retracting the lancet after it has made the incision, and many such mechanisms are known in the art, including the references previously cited and incorporated herein. One example of a retraction means is spring 150 (
The resilient means is mounted to provide relative movement to retract the lancet into the main body after making the incision. Preferably the resilient means, such as spring 150, is made from a biocompatible material, such as metal, plastic, elastic or a similar material known in the art, which does not react with the sample or interfere with the testing procedure. The resilient means may allow multiple uses if the unit is to be reused, or may be a disposable or one-use mechanism used with disposable or one-use embodiments of the unit.
The resilient means may be placed in various locations without affecting the operation of the unit. For example, the spring may be placed in the lower portion of the main body (
The withdrawal of the lancet may also be either a full or only a partial withdrawal. When fully withdrawn, the lancet is removed from the incision and returned to the retracted position protected from accidental contact by the user. However, in an alternate approach the lancet could be only partially withdrawn, thereby leaving a portion of the lancet remaining within the incision. When the lancet is only partially withdrawn, the lancet acts as a focal point for locating the blood and transferring it to the capillary. This may be useful to employ the lancet to assure that the incision remains open for the blood or other body fluid to flow out of the incision.
Referring now to
The body 105 may be made from any suitable material, and typically can be economically produced from plastics, glass, or various other materials, for example by injection molding or extrusion. The main body may be manufactured of a transparent material such as glass, plastic, polyvinyl chloride or any similar bio-compatible plastic. Alternatively, the main body may be manufactured having an opaque or solid appearing surface. In some embodiments it is desirable to have the capillary member transparent, or to include a window portion to allow the user to observe the progress of fluid filling the capillary and/or to facilitate viewing the testing of the body fluid, particularly by optical means.
Lancet 120 and spring 150 may be manufactured of any bio-compatible material such as steel, surgical stainless steel, aluminum, or titanium, as well as many other suitable materials known in the art. Preferably lancet 120 is made in a solid piece which is sufficiently sharpened to create an incision.
Preferably unit 100 is manufactured in a compact size, with annular space 130 sized to hold the desired fluid sample size. While the desired sample size will vary depending on the fluid to be sampled and the specific test desired, in preferred embodiments the volume is relatively small, and may be as small as 3 μL and less, including less than 1 μL. For transport and use, unit 100 may be packaged individually, or may be loaded in a cartridge type of container which may be loaded in an applicator for conducting multiple tests as desired.
Sterility of the unit may be enhanced by the use of a cap (
In a further alternate approach, a membrane is positioned over the distal end of the capillary member to provide a seal for the unit. The membrane is composed of a suitable material through which the lancet may extend during use. Thus, the sealing membrane does not have to be removed for use, but rather is sufficiently thin and penetrable as to remain in place when the lancing member is displaced from the retracted position to the extended position. In the latter embodiment, the sealing membrane is preferably biocompatible as well, and should not interfere with the desired functioning of the lancing member to incise the skin or the resulting capillary fluid flow. One example of such a tip is disclosed in application PCT/EP01/02198.
Illustrated in use in
The force D is then released from lancet carrier 110, and spring 150 biases lancet 120 into the retracted and protected position as shown in
Testing of the fluid sample can be accomplished using standard optical or electrochemical methods. The collected fluid can be analyzed using the full range of available procedures and equipment, including conventional test strip chemistries. For example, in one embodiment, after body fluid F contacts a micro-porous test strip 90, test strip 90 may be optically read in place or after removal to determine, for example, the blood glucose level. An optical reading of the test strip typically compares the color of the reaction of the test strip to a control chart. Alternately, test strip 90 may be removed from apparatus 100 and connected to or placed in a chemical or electronic testing apparatus. In a further alternate embodiment, unit 100 includes an optically-readable, reactive coating placed on the surface of lancet 120 or the interior circumference of body 150. Testing of body fluid F can be accomplished by the optical reading of the result of the reaction of the coating to the body fluid.
The device in alternate embodiments includes multiple testing means, for example two or more test strips 90, and includes alternate structural arrangements. Referring to
Referring now to
Referring now to
Referring now to the alternate embodiment in
In still another embodiment, shown in
After a sufficient amount of body fluid has been drawn into annular space 530, apparatus 500 is placed into analysis equipment, such as blood glucose measuring device 580 shown in
In a still further embodiment also illustrated in
A further variant on the structure of unit 100 is illustrated in
In use as shown in
A further alternate embodiment is illustrated in
An additional preferred embodiment is illustrated in
Another preferred embodiment is illustrated in
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.
The present application is a continuation of U.S. patent application Ser. No. 10/054,270, filed on Jan 22, 2002, which is claims the benefit of U.S. Provisional Patent Application No. 60/263,533, filed on Jan. 22, 2001, which are hereby incorporated by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60263533 | Jan 2001 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10054270 | Jan 2002 | US |
| Child | 10838156 | Apr 2004 | US |
