GB2300915A - Measuring erythrocyte sedimentation rates - Google Patents
Measuring erythrocyte sedimentation rates Download PDFInfo
- Publication number
- GB2300915A GB2300915A GB9509612A GB9509612A GB2300915A GB 2300915 A GB2300915 A GB 2300915A GB 9509612 A GB9509612 A GB 9509612A GB 9509612 A GB9509612 A GB 9509612A GB 2300915 A GB2300915 A GB 2300915A
- Authority
- GB
- United Kingdom
- Prior art keywords
- tube
- plug
- sample
- blood
- measurement
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 210000003743 erythrocyte Anatomy 0.000 title claims abstract description 23
- 238000004062 sedimentation Methods 0.000 title claims abstract description 18
- 210000004369 blood Anatomy 0.000 claims abstract description 39
- 239000008280 blood Substances 0.000 claims abstract description 39
- 238000005259 measurement Methods 0.000 claims abstract description 22
- 239000000443 aerosol Substances 0.000 claims abstract description 21
- 239000000463 material Substances 0.000 claims abstract description 8
- 238000000034 method Methods 0.000 claims description 9
- 239000002245 particle Substances 0.000 claims description 7
- 239000011148 porous material Substances 0.000 claims description 6
- 238000006073 displacement reaction Methods 0.000 claims description 5
- 239000011521 glass Substances 0.000 claims description 4
- 229920003023 plastic Polymers 0.000 claims description 2
- 238000011109 contamination Methods 0.000 abstract description 4
- 239000012678 infectious agent Substances 0.000 abstract description 3
- 239000007788 liquid Substances 0.000 description 11
- 238000003752 polymerase chain reaction Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 208000015181 infectious disease Diseases 0.000 description 3
- 238000003825 pressing Methods 0.000 description 3
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 2
- 239000003146 anticoagulant agent Substances 0.000 description 2
- 229940127219 anticoagulant drug Drugs 0.000 description 2
- 239000001768 carboxy methyl cellulose Substances 0.000 description 2
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 230000002458 infectious effect Effects 0.000 description 2
- 238000003780 insertion Methods 0.000 description 2
- 230000037431 insertion Effects 0.000 description 2
- -1 polypropylene Polymers 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 238000010561 standard procedure Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- KRKNYBCHXYNGOX-UHFFFAOYSA-K Citrate Chemical compound [O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O KRKNYBCHXYNGOX-UHFFFAOYSA-K 0.000 description 1
- 229920000742 Cotton Polymers 0.000 description 1
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 241000700605 Viruses Species 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000001010 compromised effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000003467 diminishing effect Effects 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000002209 hydrophobic effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000003550 marker Substances 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 239000013049 sediment Substances 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000005382 thermal cycling Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/04—Investigating sedimentation of particle suspensions
- G01N15/05—Investigating sedimentation of particle suspensions in blood
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Analytical Chemistry (AREA)
- Dispersion Chemistry (AREA)
- Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hematology (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analysing Biological Materials (AREA)
Abstract
A device for measurement of sedimentation rate of erythrocytes in a sample of blood is in the form of a tube containing a filter plug of material able to absorb aerosol droplets. The blood sample enters the tube from one end and fills the tube until it comes in contact with said plug, so that the interface between the plug and blood represents zero point for the measurement of the sedimentation rate. The plug prevents the exit of the aerosol through the upper opening of the tube and once the blood sample reaches the plug, the, flow stops precisely at the desired height. Contamination of operating technician by aerosol possibly containing infectious agents from the blood sample is therefore avoided.
Description
A DEVICE FOR MEASUREMENT OF ERYTHROCYTE
SEDIMENTATION RATE
BACKGROUND OF THE INVENTION
The measurement of erythrocyte sedimentation rate (ESR) in blood is a standard procedure widely used in clinical practice. The test is performed by filling a tube with patient's blood, which is usually first diluted with a solution of an anticoagulant such as citrate or EDTA, and then the erythrocytes are allowed to sediment for a specific time under the influence of gravity. The standard procedure is known as the Westergren method, in which a tube of 2.55 mm inner diameter and 200 mm measuring height is employed. The tube itself is usually a few centimeters longer. Other tube dimensions can used, as known in prior art.The results obtained with such tubes can be converted to the Westergren units by means of the mathematical formulae or non-linear graduation marks imprinted on such tubes or on a stand utilized in conjunction with the tubes. The reading of the sedimentation level is done visually or with help of the instruments capable of distinguishing the interface between the dark-red erythrocyte column and the upper, yellowish plasma solution. For the reading, it is important that the tube be transparent. This requirement imposes a limitation on the materials that are suitable for construction of the tube, so that glass or transparent plastics are the materials of choice.
In practice, patient's blood is withdrawn either into a syringe or into a tube under vacuum. The second way has found a wide acceptance because it greatly reduces the possibility of accidental contact with potentially infectious blood or with the needle used for the blood withdrawal. When the vacuum tube is graduated and prefilled with a solution of an anticoagulant, then the sedimentation rate can be measured directly in the vacuum tube. When the tube is not graduated, the height of erytrocyte column is measured by positioning the tube against a stand with a scale. While performing the measurement in a closed tube is the best in terms of safety to the personnel, it is not free from drawbacks. First, the erythrocytes entering the tube under vacuum are subjected to a shock, as they hit the walls of the tube. If some of them lyse, the precision of the measurement will be compromised.Second, the vacuum level must be equal in all tubes and remain constant until the time they are used. Any leakage, or a diffusion of air into the tubes, will cause variations in the volume of the withdrawn blood, affecting the height of the blood column and thus diminishing the accuracy of the measurement. Third, the amount of blood which needs to be taken for the measurement is larger than when the standard, narrow-bore Westergren tube is used. And fourth, the graduation marks are not linearly spaced, making the reading more difficult as the sedimentation rate increases.
Another way of performing the sedimentation measurement is to use a separate graduated tube. The blood solution is introduced into the tube from a container, which may be the one used for blood withdrawal with vacuum. It can also be another container into which the blood was transferred. The blood is introduced into the graduated tube by suction or by displacement. In the latter case, the tube is inserted into a container, which needs to be of cylindrical shape so that the tube, or an adaptor linked to it, fits snugly between the walls of the container. Pushing the tube downwards displaces the blood sample up. In prior art known are different devices suitable for the measurement of ESR which rely on the displacement of the blood sample into the tube. There are two important requirements that these devices need to satisfy.First, the sedimented erythrocytes must not exit at the lower end of the tube, that is the opening on this end must be closed or made such that the sedimented erythrocytes cannot leak through it. Second, the device must enable an adjustment of the height of the sample column exactly to the zero point, which is at 200 mm above the lower tube end for the Westergren method. The known devices address the two requirements in various ways.
For example, in the patent to Monn, there is a sealing rim at the inlet of the container. The height is adjusted by pressing the rim, in order to release air from the container and thus lower the sample column to the zero point. In
European Patent Application 0 024 705 Al, disclosed is a way of achieving a precise sample height by means of a movable sealing means. French Patent
Application 2 566 127 discloses a device in which the sample height is fixed by pushing, from above, a shaft which closes the communication between the sample column and the excess of blood above it. The device disclosed in
European Patent Application 0 108 724 has a sleeve attached to the graduated tube so that, after reaching the zero point, the excess of blood is spilled over into this sleeve. There are various ways of closing the lower opening.That can be achieved by pressing the tube against the bottom of the container, by using an adaptor which in contact with the bottom closes the opening, or by using a semipermeable means which allows passage of the erythrocytes into the tube but prevents leakage of the sedimented erythrocytes.
While the devices relying on the blood displacement as known in prior art have been used in practice with varying success, they are not free from drawbacks. The drawbacks are related to the complexity of manufacturing of these devices or to special skills required to use them. These shortcomings will not be addressed here in detail. There is one additional problem associated with the use of the known devices for the ESR measurement.
When a liquid flows inside a narrow tube, aerosol is formed. When the liquid is blood, this aerosol may carry infectious agents, such as viruses. Even in the case when one cannot observe any spillage of the blood sample, the operator or its surroundings may be exposed to infectious agents. The problem is compounded by the way in which the tube insertion for ESR is made.
because, when the container is kept in one hand and the tube in the other, then during insertion the upper opening of the tube comes close to the nose and mouth of the operator. This possible source of infection was not addressed in prior art, although the possibility of aerosol formation was indirectly indicated (EPA 01 08724). However, the problem cannot be solved by adding a cap (anti-spray) as proposed in US4,622,847, because this device has a vent hole through which the aerosol can escape. Other additions to the
ESR measuring tube, including a cotton plug or a porous polypropylene above or at the zero point, do not address the aerosol problem satisfactorily, because the pores of these materials are too large to completely prevent the passage of the aerosol droplets.
The aerosol-borne contamination is known as a serious source of complications when using the polymerase chain reaction (PCR), which is disclosed in US Patents 4,683,195 and 4,965,188. In this method, several pipetting steps are necessary to transfer all reagents into a test tube which is subsequently subjected to thermal cycling. The transfer is done by pipetting, where a specific volume of liquid is drawn by suction into a disposable tip and then displaced, by air, from the tip into the test tube. The aerosol droplets, which enter the suction device (pipettor), can be transferred to a next tip, and from it to the test tube. Such a contamination can lead to confusing or false results obtained by PCR.
A pipette tip able to prevent aerosol-borne contamination was disclosed in US Patent 5,156,811. A special filter plug was inserted into each disposable tip.
This plug consisted of a hydrophobic porous material, such as polyethylene, and a hydrophilic material, such as cellulose gum. Any aerosol droplets entering the plug are absorbed by the cellulose gum. If the sample liquid comes accidentally into contact with the plug, the hydrophilic particles swell and stop the flow of liquid and of air through the plug, so that the sample needs to be discarded, as specified in US Patent 5,156,811. Such pipetting tips, known as aerosol resistant tips, are widely used in most steps of the PCR method.
It has now been found that a filter plug, for example of the kind described above, can advantageously be utilized for construction of a device for the measurement of the erythrocyte sedimentation rate. If such a plug is placed inside a tube such that its lower end is at the zero point, that is 200mm above the lower end of the measuring tube, then the plug serves two purposes. First, it prevents the exit of the aerosol through the upper opening of the tube.
Second, once the blood sample reaches the plug, the flow stops. In this way the height of the sample column is precisely set at 200mm.
Accordingly, in a first aspect of the invention, there is provided a device for measurement of sedimentation rate of erythrocytes in a sample of blood, comprising:
a tube open at both of its ends, and
in the tube, a filter plug of a porous material having in its pores particles of another material able to absorb aerosol droplets and able to swell when brought in contact with the blood sample, such that when a blood sample enters the tube from one end it comes in contact with said plug, so that the interface between the plug and blood solution represents the zero point for the measurement of the sedimentation rate.
The blood sample can be introduced into the new device by any of the means known in prior art. For example, a suction means can be attached to the upper end of the tube and the sample sucked in until it reaches the plug. The sample can be introduced also by displacement. Once the sample is in the tube, it is necessary to close the lower opening of the tube in order to prevent leakage of the sedimented erythrocytes. That can be done by any means known in prior art. For example, an adaptor can be used which closes the lower tube opening after the erythrocytes have entered the tube. The closing can be also achieved by pressing the adaptor against the bottom of the container from which the blood was displaced.Alternatively, when the container has a rim, the rim can be made such that either by itself, or when pressed by the operator, it allows a release of some air as the tube is being pushed to the bottom of the container. One can use a container in which the tube fits snugly between the container walls, so that no adaptor becomes necessary. It is realised that in this second example, the released air may contain aerosol droplets. However, the amount of the released air is much less than the amount displaced through the upper opening of the tube. Second, the container is normally held in the hand, away from the nose and mouth of the operator.
Therefore, even though this second example does not completely avoid the exposure to potentially infectious aerosol, it does substantially reduce the level of the exposure.
The device described above is different from those known in the prior art for the ESR measurement. The difference is related to the use of the filter plug which contains hydrophilic particles able to absorb aqueous aerosol droplets. It is also different from the pipette device disclosed in US Patent 5,156,811. In that device, the plug is positioned so that there is certain volume of the air left, at least 10-15% of the liquid volume, between the plug and the liquid drawn into the tube. In the device according to the first aspect of the invention, the plug is positioned in the tube such that when liquid is drawn into the tube, no air is left between the plug and the liquid.
In the practice of using the device of US Patent 5,156,811, if a sample liquid accidentally comes into contact with the plug, the sample needs to be discarded together with the tube (tip). In contrast, a blood sample introduced into the preferred device according to the invention must come into contact with the filter plug. Only then can the plug function as means for setting the zero point in the present device. In addition, the tube used in the present device is generally of a constant inner diameter, whereas the tube of US Patent 5,156,811 is tapered at its lower end. This difference reflects the requirements imposed by the specific applications. The present device is used for measurement of a column of sedimented particles, while the purpose of the prior art device is to withdraw and then displace a precise volume of liquid.
In a second but less preferred aspect of the invention, the filter plug can be placed above the zeropoint mark. It will then function only as a means to prevent the exit of the aerosol droplets. A marker must then be provided to mark the zero point.
The two aspects of the invention are illustrated in the accompanying drawings, in which
Figure 1 and Figure 2 are schematic representations of the upper end of the an ESR tube in accordance with the first and second aspects of the invention respectively.
In the embodiment shown in Figure 1, a porous plug (1) is positioned at the top of a glass tube (2), such that the bottom of the plug is exactly 20cm from the bottom of the tube.
In the embodiment illustrated in Figure 2, the glass tube (2) is slightly longer, and a datum indicator (3) is positioned so as to indicate the zero point, again 20cm from the base of the tube. Porous plug (1) is in this case positioned at a higher position at the top of the tube, in order to prevent the egress of aerosol particles.
Claims (20)
1. A device for measurement of sedimentation rate of erythrocytes in a sample of blood, comprising:
a tube open at both of its ends, and
in the tube, filter plug of a porous material having in its pores particles of another material able to absorb aerosol droplets and able to swell when brought in contact with the blood sample.
2. A device as claimed in Claim 1, wherein the plug is positioned in the tube such that when a blood sample enters the tube from one end it comes in contact with said plug, so that the interface between the plug and blood solution provides the zero point for the measurement of the sedimentation rate.
3. A device as claimed in Claim 1, wherein the plug is positioned in the tube above the zero point for the measurement.
4. A device as claimed in any one of the preceding
Claims, wherein the tube is made from glass.
5. A device as claimed in any one of Claims 1 to 3 wherein the tube is made of transparent plastic.
6. A device as claimed in any one of the preceding
Claims, wherein the particles in the plug are such as to swell in contact with a blood sample sufficiently quickly to prevent downwards flow of the sample.
7. A device as claimed in any one of the preceding
Claims, including means for closing the lower end of the tube after introduction of the sample, by contact with the bottom of a container.
8. A device as claimed in Claim 5, wherein the said means comprises an adaptor attached to the lower end of the tube.
9. A device as claimed in any one of the preceding
Claims, including a semi-permeable means adapted to allow introduction of the sample into the tube but to prevent leakage of the sedimented erythrocytes.
10. A device as claimed in any one of the preceding
Claims, wherein the tube is longer than 20cm.
11. A device as claimed in Claim 10, wherein the device is from 20.5 to 24 cm in length.
12. A device as claimed in any one of the preceding
Claims, where said plug is placed at such a position in the tube that the ratio between the distance from one tube end to the plug and the distance from the other tube end to the plug is at least 5:1.
13. A device as claimed in any one of the preceding
Claims, wherein the internal diameter of said tube is 2.55mm.
14. A method for measuring the sedimentation rate of erythrocytes, comprising using a device of any one of the
Claims 1 to 11.
15. A method as claimed in Claim 14, wherein the sample is introduced into the tube by displacement.
16. A method as claimed in Claim 14 or Claim 15, wherein reading of the height of the sedimented erythrocyte column is done visually.
17. A method as claimed in Claim 14 or Claim 15, wherein reading of the height of the sedimented erythrocytes is done by an instrument.
18. A device for measurement of sedimentation rate of erythrocytes in a tube, wherein said device comprises within the tube a filter plug of a material able to capture aerosol droplets.
19. A device for measurement of sedimentation rate of erythrocytes in a sample of blood, substantially as hereinbefore described with reference to the accompanying drawings.
20. A method for measurement of sedimentation rate of erythrocytes in a sample of blood, substantially as hereinbefore described with reference to the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9509612A GB2300915A (en) | 1995-05-12 | 1995-05-12 | Measuring erythrocyte sedimentation rates |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9509612A GB2300915A (en) | 1995-05-12 | 1995-05-12 | Measuring erythrocyte sedimentation rates |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9509612D0 GB9509612D0 (en) | 1995-07-05 |
| GB2300915A true GB2300915A (en) | 1996-11-20 |
Family
ID=10774343
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9509612A Withdrawn GB2300915A (en) | 1995-05-12 | 1995-05-12 | Measuring erythrocyte sedimentation rates |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2300915A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998023943A1 (en) * | 1996-11-28 | 1998-06-04 | Zakrytoe Aktsionernoe Obschestvo Tsentr 'analiz Veschestv' | Method of recording blood sedimentation and device for recording blood sedimentation |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3864979A (en) * | 1973-03-30 | 1975-02-11 | Becton Dickinson Co | Blood sedimentation tube barrier |
| GB1567325A (en) * | 1977-03-28 | 1980-05-14 | Guest Medical & Dental Prod | Sedimentation tests |
| EP0055234A2 (en) * | 1980-12-23 | 1982-06-30 | Ab Tesi | Method of time-marking sedimentation processes and device for carrying out the method |
| US5019349A (en) * | 1985-11-08 | 1991-05-28 | Issei Suzuki | Pipe for measuring erythrocyte sedimentation rate |
| US5156811A (en) * | 1990-11-07 | 1992-10-20 | Continental Laboratory Products, Inc. | Pipette device |
-
1995
- 1995-05-12 GB GB9509612A patent/GB2300915A/en not_active Withdrawn
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3864979A (en) * | 1973-03-30 | 1975-02-11 | Becton Dickinson Co | Blood sedimentation tube barrier |
| GB1567325A (en) * | 1977-03-28 | 1980-05-14 | Guest Medical & Dental Prod | Sedimentation tests |
| EP0055234A2 (en) * | 1980-12-23 | 1982-06-30 | Ab Tesi | Method of time-marking sedimentation processes and device for carrying out the method |
| US5019349A (en) * | 1985-11-08 | 1991-05-28 | Issei Suzuki | Pipe for measuring erythrocyte sedimentation rate |
| US5156811A (en) * | 1990-11-07 | 1992-10-20 | Continental Laboratory Products, Inc. | Pipette device |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998023943A1 (en) * | 1996-11-28 | 1998-06-04 | Zakrytoe Aktsionernoe Obschestvo Tsentr 'analiz Veschestv' | Method of recording blood sedimentation and device for recording blood sedimentation |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9509612D0 (en) | 1995-07-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |