Analyzer cartridge with capillary wiper

Abstract

A disposable test cartridge and method for a point-of-care analyzer includes a cartridge body having a plurality of chambers where each of the plurality of chambers has an opening at a top of the cartridge body, a cartridge cover connected to the cartridge body where the cartridge cover has a capillary-receiving aperture, a capillary wiper disposed within the capillary-receiving aperture where the capillary-receiving aperture is aligned with one of the plurality of chambers of the cartridge body, and a capillary element removably insertable into the cartridge cover where the capillary element has a capillary tube that extends into the capillary-receiving aperture and through the capillary wiper where a tip portion of the capillary tube extends into the cartridge body.

Claims

1. A capillary wiper for a disposable test cartridge having a cartridge body with a plurality of chambers, a cartridge cover connected to the cartridge body wherein the cartridge cover has a capillary-receiving aperture, and a capillary element having a capillary tube that extends into the capillary-receiving aperture wherein the capillary element is removably insertable into the capillary-receiving aperture of the cartridge cover for use in a point-of-care analyzer, comprising: the cartridge body; the cartridge cover; and the capillary wiper between the cartridge cover and the cartridge body, the capillary wiper further comprising: a tubular upper portion having an upper portion opening that mates with a cover tube extension connected to the capillary-receiving aperture of the cartridge cover; an elastomeric tapered lower portion having a base end and an apex end wherein the apex end has a lower portion aperture that is smaller than the upper portion opening and wherein the base end is connected to the tubular upper portion; a plurality of upper portion protrusions on an outside surface of the tubular upper portion at a junction between the tubular upper portion and the elastomeric tapered lower portion wherein the plurality of upper portion protrusions are compressible between the cartridge cover and the cartridge body, the plurality of upper portion protrusions extend along the tapered lower portion a predefined distance; and an open pathway between the upper portion opening and the lower portion aperture defining a capillary wiper volume for receiving the capillary tube therethrough, the upper portion opening having a larger cross-sectional area than the capillary tube and the lower portion aperture having a smaller cross-sectional area than the capillary tube whereby the lower portion aperture expands around the capillary tube.

2. The capillary wiper of claim 1 wherein the tubular upper portion is made of an elastomeric material.

3. The capillary wiper of claim 1 wherein the plurality of upper portion protrusions disposed in a radial array at the junction between the tubular upper portion and the tapered lower portion.

4. The capillary wiper of claim 3 wherein the plurality of upper portion protrusions are made of an elastomeric material.

5. The capillary wiper of claim 1 wherein the tubular upper portion is attached to the cover tube extension of the cartridge cover of the disposable test cartridge.

6. The capillary wiper of claim 1 wherein the capillary wiper is over-molded onto the cover tube extension of the cartridge cover of the disposable test cartridge.

7. The capillary wiper of claim 1 wherein the open pathway within the tapered lower portion is tapered.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a perspective view of one embodiment of the present invention showing a disposable test cartridge for a point-of-care analyzer and a point-of-care analyzer.

(2) FIG. 2 is an enlarged, partial cross-sectional view of the disposable test cartridge of FIG. 1 showing the capillary wiper.

(3) FIG. 3 is an exploded perspective view of the disposable test cartridge of FIG. 1.

(4) FIG. 4 is an exploded side view of the disposable test cartridge of FIG. 1.

(5) FIG. 5 is an enlarged bottom perspective view of one embodiment of the capillary wiper shown in FIG. 3 showing the tapered lower portion with the lower portion opening.

(6) FIG. 6 is an enlarged reverse perspective view of the capillary wiper shown in FIG. 5.

(7) FIG. 7 is an enlarged front plan view of the capillary wiper shown in FIG. 5.

(8) FIG. 8 is an enlarged front cross-sectional view of the capillary wiper shown in FIG. 5.

(9) FIG. 9 is an enlarged bottom view of the capillary wiper shown in FIG. 5.

(10) FIG. 10 is an enlarged top view of the capillary wiper shown in FIG. 5.

(11) FIG. 11 is an enlarged cross-sectional view of the capillary element containing a sample and being inserted into the cartridge cover and capillary wiper.

(12) FIG. 12 is an enlarged cross-sectional view of the capillary element containing a sample and being inserted into the cartridge cover and capillary wiper showing the capillary tip about to push through the capillary wiper.

(13) FIG. 13 is an enlarged cross-sectional view of the capillary element containing a sample and being inserted into the cartridge cover and capillary wiper showing the capillary tube extending through the capillary wiper.

(14) FIG. 14 is a graphic representation of the data in Table 1 showing the results for total cholesterol where a capillary wiper was not included in the disposable test cartridge.

(15) FIG. 15 is a graphic representation of the data in Table 1 showing the results for triglycerides where a capillary wiper was not included in the disposable test cartridge.

(16) FIG. 16 is a graphic representation of the data in Table 1 showing the results for high-density lipoproteins where a capillary wiper was not included in the disposable test cartridge.

(17) FIG. 17 is a graphic representation of the data in Table 3 showing the results for total cholesterol where a capillary wiper was included in the disposable test cartridge.

(18) FIG. 18 is a graphic representation of the data in Table 3 showing the results for triglycerides where a capillary wiper was included in the disposable test cartridge.

(19) FIG. 19 is a graphic representation of the data in Table 3 showing the results for high-density lipoproteins where a capillary wiper was included in the disposable test cartridge.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

(20) The preferred embodiments of the present invention are illustrated in FIGS. 1-19. FIG. 1 shows one embodiment of a disposable test cartridge 10 for use in a point-of-care analyzer 200. Test cartridge 10 includes a cartridge body 20, a cartridge cover 40, a capillary element 60, and a capillary wiper 80 (not shown). Capillary element 60 is removable from the cartridge cover 40.

(21) Turning now to FIG. 2, there is illustrated a partial cross-sectional view of a portion of the disposable test cartridge 10 showing the capillary element 60 and the capillary wiper 80. Capillary element 60 includes a capillary element body 62 having a top body surface 64, a depending capillary element finger 66 defining a capillary element volume 68, a top body opening 70 that communicates with capillary element volume 68, and a capillary tube 72 extending from a finger end 66a. Capillary element volume 68 decreases in cross-sectional area from top body opening 70 to finger end 66a. It is understood that capillary element volume 68 is open and continuous from top body opening 70 and through capillary tube 72. Capillary element volume 68 may have a continuous taper or a stepped taper or a plurality of concentric, reduced diameters. Capillary wiper 80 has an upper portion 82 and a tapered lower portion 88. As can be seen, capillary tube 72 extends through tapered lower portion 88 of capillary wiper 80 and into one of a plurality of chambers 22 within cartridge body 20.

(22) FIGS. 3 and 4 are exploded views of disposable test cartridge 10 shown in FIG. 1. FIG. 3 is a front perspective view and FIG. 4 is a side cross-sectional view of test cartridge 10. Cartridge body 20 has a plurality of chambers 22 extending below a cartridge body top surface 24, each having an opening 26. Each of the plurality of chambers 22 has a specific purpose such as receiving the test sample, holding a chemical reagent adapted for a specific test, one or more calibration standards, and the like. For example, disposable test cartridge 10 in combination with the point-of-care analyzer may provide test results that include, but are not limited to, HbA1C, eAG, total cholesterol, HDL cholesterol, triglycerides, LDL cholesterol, cholesterol/HDL ratio, non-HDL cholesterol, urine albumin, urine creatinine, and albumin/creatinine ratio. More specifically and referencing FIG. 4, the plurality of chambers 22 of the cartridge body 20 are arranged in the following order. Chamber 22a contains a disposable pipette tip (not shown), chamber 22b is the sample receiving chamber into which capillary tube is inserted and the sample deposited, chamber 22c to 22f contain various reagents for determining a predefined set of test results, and chamber 22g is the mixing and measuring chamber for sample and reagents. Not shown in FIGS. 3 and 4 is a foil seal that covers all of the openings 26 of the plurality of chambers 22 to prevent contamination of the chambers 22 and reagents therein.

(23) Capillary wiper 80 has upper portion 82 and tapered lower portion 88. Upper portion 82 and tapered lower portion 88 are tubular, meaning that capillary wiper 80 defines a capillary wiper volume 94. A lower volume portion 96 is adapted to receive a portion of capillary finger element 66 and capillary tube 72.

(24) Cartridge cover 40 has a cover top surface 42 with a plurality of descending cover sides 44 forming a cover recess 46. Extending upward from cover top surface 42 is cover extension 48 that also forms a recess portion 46a of cover recess 46. Cover extension 48 has a stepped extension portion 50 with an extension portion top surface 52 and a capillary-receiving aperture 54 that communicates with portion 46a of cover recess 46. A cover tube extension 56 extends a predefined distance from capillary-receiving aperture 54 into recess portion 46a. Cover tube extension 56 mates with upper portion 82 of capillary wiper 80. Cover recess 46 receives a top portion 28 of cartridge body 20 and locked in place with releasable tabs 28a. Cartridge cover 40, in this embodiment, also has a back side extension 58 with a back extension end 58a that is received within a cover receiving slot 28 located on cartridge body 20. Back extension end 58a has a small sharp point 58b (more clearly shown in FIG. 3) that is used by the point-of-care analyzer to pierce the foil covered openings 26 of the plurality of chambers 22 during use of the disposable test cartridge 10. The pipette tip (not shown) is used by the analyzer to dilute the sample and select a predefined quantity of the diluted sample for mixing with the test reagents and subsequent measurement in chamber 22g. It is understood that the analyzer removes cartridge cover 40 and uses the back extension end 58a to pierce the foil seal once the capillary tube 72 and sample are inserted into and assembled with cartridge cover 40 and then the disposable test cartridge 10 is inserted into the analyzer 200.

(25) As previously discussed, capillary element 60 has element body 62, top body surface 64, depending capillary element finger 66 defining a capillary element volume 68, top body opening 70 that communicates with capillary element volume 68, and a capillary tube 72 extending from a finger end 66a. Capillary tube 72 has a tube distal end 72a that may optionally be tapered.

(26) Turning now to FIGS. 5-8, there is illustrated various enlarged views of capillary wiper 80. Capillary wiper 80 has two major portions, the upper portion 82 and a tapered lower portion 88 that are mated to each other at a junction 85. Tapered lower portion 88 has a base end 88a and an apex end 88b where apex end 88b has lower portion aperture 88c. At the junction 85 between upper portion 82 and tapered lower portion 88, there are a plurality of optional upper portion protrusions 82b that extend from the upper portion 82 at the junction 85 along the tapered lower portion 88 for a predefined distance. Upper portion protrusions 82b are spaced from each other in a radial array that provides a limited amount of compressibility. Upper portion protrusions 82b tend to stabilize cartridge wiper 80 when assembled between cartridge cover 40 and cartridge body 20.

(27) Capillary wiper volume 94 has lower volume portion 96 and an upper volume portion 98 in communication with lower volume portion 96. Lower volume portion 96 is optionally tapered from its junction with upper volume portion 98 to lower portion aperture 88c. One advantage of having a tapered lower volume portion 96 is it provides a centering guide for capillary tube 72. It is contemplated that an untapered cylindrical volume having a cross-sectional diameter greater than capillary tube 72 may also be used. In the embodiment illustrated, upper volume portion 98 is divided into two different cross-sectional areas, 98a and 98b, but could also have only one or more that two different cross-sectional areas depending on the structural configuration of cartridge cover 40. In the embodiment illustrated, upper volume portion 98a has a larger cross-sectional diameter than upper volume portion 98b to better fit over cover tube extension 56 and provides a snug fit so that cover tube extension 56 retains capillary wiper 80 when cartridge cover 40 is removed during processing of the sample in disposable test cartridge 10 by point-of-care analyzer 200.

(28) FIG. 9 illustrates a distal end view of capillary wiper 80. In this view, the radial positioning of optional upper portion protrusions 82b is clearly shown. Apex end 88b includes lower portion aperture 88c and tapered lower portion 88. FIG. 10 illustrates a proximal end view of capillary wiper 80. In this view, the concentric nature of capillary wiper volume 94 is shown. At the furthest point, there is shown lower portion aperture 88c and apex end 88b. Tapered lower portion 88 in this embodiment defines lower volume portion 96 as having a tapered shape which extends from upper volume portion 98 to apex end 88b. In this embodiment, upper volume portion 98 is divided into upper volume portion 98a and upper volume portion 98b.

(29) Turning now to FIGS. 11-13, there is illustrated capillary tube 72 containing a sample 300 to be tested where the sample for testing is inside capillary tube 72 and sample 310 on the outside surface of capillary tube 72. It is this sample 310 on the outside surface of capillary tube 72 that potentially leads to erroneous test results. Typically, a trained technologist would carefully wipe the outside of capillary tube 72 to remove the sample 310 on the outside surface of capillary tube 72, being careful not to touch tube distal end 72a. If the sample 310 on the outside surface is not removed, the transfer of the sample 300 and 310 into the dilution chamber 22b would cause the sample to have a higher ratio of sample to diluent thus causing the test results to have higher values than they should have. If the distal end 72a is accidentally touched while wiping the outside surface of capillary tube 72, an amount of sample within capillary tube 72 may be withdrawn leaving a smaller amount of sample available for dilution. This causes the sample to have lower values than they should have. Because point-of-care analyzer is designed to provide accurate measurements based on a specific predefined sample size, any over-filling of sample in the dilution chamber 22b caused by sample remaining on the outside surface of capillary tube 72 or any under-filling of sample in dilution chamber 22b caused by the inadvertent removal of a small amount of sample from the capillary tube 72 leads to erroneous results. This is even more of a problem for point-of-care analyzers since these types of analyzers are for use in a doctor's office, which do not employ highly trained technologists, who are used typically in central labs where hundreds of tests are run daily. These highly trained technologists have the techniques that ensure consistent results. The typical person in a doctor's office that would obtain the blood and/or urine sample for measurement by the point-of-care analyzer have other duties such as nurses, physician assistants, medical assistants, and the like that are not highly trained as lab technologists. The consequence is a higher number of inaccurate and erroneous results that could lead to improper diagnose and treatment of patients.

(30) Sample Data Showing Erroneous Results

(31) The use of capillary wiper 80 provides a marked improvement in results obtained from a point-of-care analyzer when operated by persons other than a trained instrument technologist. Two sets of test data were obtained using a point-of-care analyzer (Allegro by Nova Biomedical Corporation). The first set involved the use of a disposable test cartridge without the integral capillary wiper 80 and the second set involved the use of a test cartridge with the integral capillary wiper 80. To simulate the effect of using a person that is not a trained instrument technologist, some of the capillary tubes 72 were intentionally over dosed with sample so that some sample was left on the outside surface of the capillary tube. This simulates the improper wiping and/or lack of wiping the outside surface of the capillary tube after obtaining a sample for testing. The tests consisted of ten (10) whole blood samples run with the integral capillary wiper 80 and ten (10) whole blood samples run without the integral capillary wiper. Measurements were made for total cholesterol (TC), triglycerides (TG), and high-density lipo-proteins (HDL). Standard deviation (STDEV), average value (AVG) and percent coefficient of variation (% CV) were determined for all sample points, for overdosed capillary tubes and for properly dosed capillary tubes for each set of test measurements.

(32) Table 1 below contains the test data for the samples run using a disposable test cartridge with no capillary wiper. The letters “OD” under method represents a test sample with a capillary tube having sample on its outside surface (i.e. overdosed).

(33) TABLE-US-00001 TABLE 1 TC TG HDL Sample mg/dL mg/dL mg/dL Method 1 257 81 77 OD 2 177 75 51 3 225 80 67 OD 4 182 56 51 5 184 62 51 OD 6 179 61 45 7 226 69 63 OD 8 174 59 48 9 205 61 52 OD 10 167 59 42

(34) Table 2 is discloses the standard deviation, average values and percent coefficient of variation for the values in Table 1.

(35) TABLE-US-00002 TABLE 2 All Points STDEV 29.5 9.3 10.9 AVG 197.6 66.3 54.7 % CV 14.9% 14.0% 19.9% Overdosed Capillaries STDEV 27.2 9.6 10.9 AVG 219.4 70.6 62.0 % CV 12.4% 13.5% 17.5% Properly dosed Capillaries STDEV 5.7 7.5 3.9 AVG 175.8 62.0 47.4 % CV 3.3% 12.1% 8.3%

(36) FIGS. 14-16 are schematic representations of the test data for each category (i.e. TC, TG and HDL) disclosed in Table 1. Indicators were added to the drawings to bring attention to those values for the capillary tubes that had sample on the outside surface. As can be seen from the test data, each of the ‘overdosed’ capillaries (indicated by arrows in the FIGS. 14-19) reported higher values for total cholesterol, triglycerides and high-density lipo-proteins. Even the values for all tests (both standard dose and over-dosed samples) taken together reported higher values for total cholesterol, triglycerides and high-density lipo-proteins than for the properly-dosed capillaries only. The standard deviations, the average values and the percent coefficient of variation had significantly higher values for the capillary tubes with sample on the outside surface (i.e. overdosed capillaries) than the values for the capillary tubes that were properly dosed.

(37) Table 3 below contains the test data for the samples run using a disposable test cartridge with a capillary wiper.

(38) TABLE-US-00003 TABLE 3 TC TG HDL Sample mg/dL mg/dL mg/dL Method 1 169 69 40 OD 2 173 63 41 3 177 62 51 OD 4 176 63 46 5 174 69 44 OD 6 180 62 50 7 173 62 51 OD 8 177 61 49 9 174 64 41 OD 10 174 71 42

(39) Table 4 discloses the standard deviation, average values and percent coefficient of variation for the values in Table 3.

(40) TABLE-US-00004 TABLE 4 All Points STDEV 3.0 3.6 4.5 AVG 174.7 64.6 45.5 % CV 1.7% 5.6% 9.8% Overdosed Capillaries STDEV 2.9 3.6 5.3 AVG 173.4 65.2 45.4 % CV 1.7% 5.5% 11.7% Properly dosed Capillaries STDEV 2.7 4.0 4.0 AVG 176.0 64.0 45.6 % CV 1.6% 6.3% 8.9%

(41) FIGS. 17-19 are schematic representations of the test data for each category (i.e. TC, TG and HDL) disclosed in Table 3. Indicators were added to the drawings to bring attention to those values for the capillary tubes that had sample on the outside surface. As can be seen from the test data, each of the ‘overdosed’ capillaries reported very similar values for total cholesterol, triglycerides and high-density lipo-proteins. Even the values for all tests (both standard dose and over-dosed samples) taken together reported similar values for total cholesterol, triglycerides and high-density lipo-proteins to those for the properly-dosed capillaries only. The standard deviations, the average values and the percent coefficient of variation had significantly similar values for the capillary tubes with sample on the outside surface (i.e. overdosed capillaries) to the values for the capillary tubes that were properly dosed.

(42) The conclusion from this test data is that the use of a disposable test cartridge containing a capillary wiper provides consistently better and fewer erroneous results. Accordingly, even when a person that is not trained as an instrument technologist performs the acquisition and testing of a sample using a capillary tube for a point-of-care analyzer, the lack of wiping any excess sample from the capillary tube before inserting the capillary tube with sample into the disposable test cartridge still provides relatively accurate results as seen from the standard deviation, average value and percent coefficient of variation between the overdosed and properly dosed capillary tubes. Furthermore, not wiping the outside surface of capillary tube 72 prevents the inadvertent and accidental removal of sample from inside capillary tube 72.

(43) A method of reducing erroneous results from a point-of-care analyzer 200 having a disposable test cartridge 10 for receiving a test sample will now be discussed. The method includes providing a tubular, capillary wiper 80 having a pipette-shaped longitudinal cross-section with a tapered, elastomeric bottom portion 88 and a top opening 84 having a cross-sectional area greater than the cross-sectional area of a capillary tube 72 used with the disposable test cartridge 10 and a bottom opening 88c having a cross-sectional area smaller than the cross-sectional area of the capillary tube 72. The method also includes disposing the capillary tube 72 into and through the capillary wiper 80 whereby the bottom opening 88c of the capillary wiper 80 expands around capillary tube 72 and removes excess sample from an outside surface of the capillary tube 72 as the capillary tube 72 is pushed through the bottom opening 88c and prevents the excess sample from being added to or with the sample within the capillary tube 72.

(44) For the illustrated disposable test cartridge 10, the method will now be discussed. A disposable test cartridge 10 designed for the point-of-care analyzer 200 is obtained. A finger prick sample is created by lancing a finger of a patient or a urine sample is obtained from the patient depending on the specific test cartridge 10 used, which are designed and configured with reagents for specific tests and sample types. For purposes of this explanation, the assumption will be that a blood sample from a finger prick is obtained and the disposable test cartridge 10 specific for this type of sample and associated tests is used. For tests using a urine sample, the method is very similar except that a finger prick is not used. The capillary element 60 is removed from cartridge cover 40 of disposable test cartridge 10. Capillary tube 72 of capillary element 60 is touched to the drop of blood sample to fill capillary tube 72. Capillary element 60 is returned to disposable test cartridge from which it came. In other words, capillary element 60 is inserted through capillary-receiving aperture 54 in extension portion top surface 52 of stepped extension portion 50 of cover extension 48 of disposable test cartridge 10 and seated in stepped extension portion 50. During the insertion and setting process, capillary tube 72 is inserted through lower portion aperture 88c located in apex end 88b of capillary wiper 80. Because the cross-sectional area of lower portion aperture 88c is smaller than the cross-sectional area of capillary tube 72, lower portion aperture 88c acts like a squeegee against the outside surface of capillary tube 72 and prevents any sample inadvertently disposed on the outside surface of capillary tube 72 from entering and being deposited into chamber 22b of test cartridge 10. Cartridge 10 is then inserted into point-of-care analyzer 200 for the automatic testing of the sample. Because capillary wiper 80 removes any sample from the outside surface of capillary tube 72, erroneous results are prevented from an “over-filling” of chamber 22b with sample. Likewise, since capillary tube 72 is not wiped by the user, there is no, or very little, chance that any sample within capillary tube 72 is removed inadvertently, which would lead to erroneous results from an “under-filling” of chamber 22b with sample.

(45) Thus, the present invention provides a point-of-care analyzer with disposable test cartridge(s) that can be used by persons other than a highly trained instrument technologist and still obtain accurate results in a timely manner in a doctor office setting similar to the results obtained from tests performed by highly trained instrument technologists in central testing laboratories.

(46) Although the preferred embodiments of the present invention have been described herein, the above description is merely illustrative. Further modification of the invention herein disclosed will occur to those skilled in the respective arts and all such modifications are deemed to be within the scope of the invention as defined by the appended claims.