240941 1
BLOOD COLLECTION SYSTEM
. The present invention relates to a system for a collection of a sample in small quantities for .e testing purposes. ë :..DTD: While the system can be used to take samples of other liquids, its primary use is to collect blood samples, most particularly, but not exclusively, from infants and neonates. In these .
cases, it is common for a blood sample to be produced by a prick in the heel of the infant with a sample of the blood behlg collected by smearing onto a slide or scooping into a container. Neither one of these methods is satisfactory, as the infant is often required to produce lar more blood than is required for the test to be performed, and the production of this excess blood may cause the infant some distress.
Furthermore, these methods of collection of the blood may contaminate the sample, or may spread the blood to other areas where, if the donor is contaminated with HIV, hepatitis or other such diseases transmissible by blood contact, it could pose a risk to the persons collecting the sample.
Other uses for the system are taking samples from more elderly patients, where blood may be collected from an earlobe or a finger in otherwise similar manner. Also, accident victims may need their blood to be tested and this system provides a quick and easy way to obtain a small sample for testing.
The amount ot' blood required for most modern blood testing procedures is very small, particularly when a test is based on reactions with antibodies or other biochemical reactions.
I'he amount may be as small as 1()()1. ..
It is known from co-pending application No. (1B2368299A to provide a capillary tube for storage of blood samples. In this application, the capillary tube has an internal single . helically wound filament of glass which aids introduction blithe sample into the tube. The -...
capillary tube is also provided with an internal coating of heparin, its lithium salt or other . anti-coagulant which serves to maintain the blood stored in a liquid condition.
It is an object of the present invention to provide a blood collection system utilising a development of such a tube to collect a sample and deliver it to a phial for subsequent testing.
According to a first aspect of' the present invention, there is provided a system for collecting a sample comprising a capillary tube having at least one filament wound helically therewithin and bent at an intermediate point of its length, a collection container and a cover for said container including a aperture through which one end of said tube may pass and air inlet means.
Preferably said cover is provided with a sealing plug to seal the aperture and the air inlet means.
The tube may be bent at an obtuse angle, preferably between 100 and 150 , ideally in the region of 120 .
The tube may comprise three or more helically wound filaments.
According to a second aspect of the present invention there is provided a method of collecting a sample comprising the steps ol providing a system as described above, inserting : .. a first end of the tube through the cover into the container and so applying an opposite end of ë the tube to a sample to be collected that the bend of the tube is uppermost. ë
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After collection of the sample, the container may be closed sealingly. : . .
According to a third aspect of the present invention there is provided a capillary tube comprising a substantially cylindrical tube and a plurality of filaments, each spaced substantially equiangularly from the next and extending along a substantially helical path from an end of said tube to an opposing end thereof and in contact with an interior surface of a tube along substantially the whole length of the filament.
An internal surface of said tube and said filaments may be coated with heparin or some other anticoagulant.
An embodiment of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional elevation of a blood sampling system embodying the invention in operation; Figure 2 is an end view of a vial cap of the system shown in Figure 1; Figure 3 is an end view oi'the vial cap shown in Figure 2 with a capillary tube in place; Figure 4 is an end view of a capillary tube of the blood sampling system shown in Figure 1; and Figure 5 is a cross-sectional elevation of a part of the capillary tube shown in Figure 4. .
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Referring now to the Figures and to Figure 1 in particular a blood sampling system comprises - . a cylindrical glass vial I or similar container with a cap 2 of rubber or other elastomer -..
plugging its open end. An outer sleeve 3 of the cap 2 hugs an outer surface of the vial 1, : . while an inner sleeve 4 of the cap 2 is in sealing contact with an inner surface of the vial 1. . . .
The cap 2 is thus held securely in place and any liquid in the vial 1 cannot seep between the vial 1 and the cap 2. The size of the phial 1 as shown is exaggerated for clarity. Given the size of the sample to be collected, it may be smaller than indicated.
cylindrical recess 5 is provided centrally of an end face of the vial cap 2, and an aperture 6 having the general iorm ol'a four-pointed star extends through the cap 2 from a floor of the recess 5, as shown in Figure 2. The cap 2 is provided with a captive plug 7 attached thereto, which may be litted into the recess 5 so as to block the aperture 6 completely when the sample has been captured.
A capillary tube 8 extends through the aperture 6 in the cap 2 towards an end of the vial 1 remote therefrom. As shown in Figure 3, the presence of the capillary tube 8 opens out the aperture 6 so that four generally triangular orifices 9 are formed around the capillary tube 8.
These allow air to be expelled from the vial 1 when a liquid sample is collected therein.
The capillary tube 8 has a bend 1 () at roughly a third of the way along its length, dividing it into a first, shorter part l I and a second, longer part 12, extending at an angle of about 120 each to the other.
In use, the longer part 11 of the bent capillary tube 8 is inserted through the aperture 6 in the cap 2 of the container 1 and pushed through until it reaches the base of the container 1. . A.
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The capillary tube 8 is of glass and is provided with three solid glass filaments 14 extending .
. along its interior surface 13 (see Figure 4). Each filament 14 traces a substantially helical .e..
path from one end of the capillary tube 8 to the other (see Figure 5). The presence of these : .. filaments 14 greatly enhances the rate at which a liquid is taken up into the tube 8 by . .
capillary action' and the rate at which it passes along the tube 8. While even one such filament has a beneficial effects a plurality produce further improvements, and four, five or even more such filaecnts are envisaged in alternative suitable capillary tubes.
In order to collect a sample of blood or other fluid, the free end of the capillary tube 8 is offered to a sample 15 at an angle somewhere in the region of 60 to the vertical, with the container l being held at a downward angle adjacent to the sample 15. The blood or other liquid sample 15 will flow by capillary attraction upwardly along the first part I I of the capillary tube 8. Flow will then continue round the bend 10 and down into the container 1.
Once flow has been established, the tube 8 acts as a siphon, though the capillary action continues to enhance the flow rate.
When a sufficient sample 16 has been collected in the container 1, the capillary tube 8 may be withdrawn from the blood or other sample 15. The container 1 can then be moved to the vertical and shaken or tapped to expel any blood remaining in the capillary tube 8 into the container 1. The capillary tube 8 can then be removed from the container I and disposed of in a safe manner while the container 1 is plugged with the captive plug 7.
If, during the above procedure, the flow of blood or sample should be broken at source, the .
procedure can be suspended until more blood is available. When it is, in order to avoid an airlock, the system can be inclined further so that the blood in the capillary tube flows back to . the free end, whereupon the tube is again offered to the source and collection in the container -..
can resume. :
Preferably, an inner surf-ace oi the capillary tube 8 is coated with heparin, its lithium salt or another anti-coagulant material. This acts against premature coagulation of blood within the tube 8, and will mix into the blood sample 16 being collected within the vial 1, to enhance its storage stability.
Other reagents may be provided, for example biochemical test reagents, either held within the vial 1, or as a coating for the inner surface of the capillary tube to enhance mixing into the blood.