WO1989009025A1

WO1989009025A1 - Blood collecting unit and its use

Info

Publication number: WO1989009025A1
Application number: PCT/SE1989/000165
Authority: WO
Inventors: Maria Hansby
Original assignee: Maria Hansby
Priority date: 1988-03-31
Filing date: 1989-03-31
Publication date: 1989-10-05
Also published as: SE8801199L; SE460697B; SE8801199D0

Abstract

Blood collecting unit comprising a tube (main tube), said main tube having at one end thereof a cannula to be inserted into the vein of a blood donor and having at its other end a vessel for collecting blood from the donor. The characteristic feature is that the main tube has a bifurcation situated between the cannula and vessel and provided with a second tube, so-called secondary tube, which (a) at its outer end provides means for collecting minor amounts of blood (blood samples) and (b) is equipped with a device preventing liquid flow through the secondary tube and constructed in such a manner that it can be opened up by being acted upon externally, so that then liquid is enabled to flow through the secondary tube.

Description

Blood collecting unit and its use

The invention relates to improvements in sampling procedures performed when blood is collected from blood donors.

Technical background

Blood collecting units basically comprise the following com¬ ponents: (i) a cannula to be inserted into the vein of a blood donor, (ii) a vessel for collecting the blood, and (iii) a tube connecting the cannula and vessel with each other so as to permit blood flow from the donor via the cannula system to thus provide the possibility that blood collected by means of said unit is stored for more than one 24-hr day. The tube and vessel are usually made of plastics. The collector vessel takes the form of an approximately 0.5 - 1 lit. bag wich contains anticoagulants, generally in the form of a solution. Additional vessels (bags) may be connected to the blood collector vessel for the purpose of blood processing. It is a common practice to subject the blood to centrifugation so as to obtain erythrocytes, plasma and white blood cells in the form of individual phases which then can be separated from one another.

Problems associated with blood collecting units of the types currently in use

Blood-borne contagion events have now for a long time been a troublesome problem in all medical workers' routines. And the situaion can hardly be said to have improved after the first cases of AIDS were reported. Protection is being sought nowadays in all and any conceivable manner. In many places particular written guidelines have been drawn up for a correct handling of blood.

Similar guidelines are to be found in Swedish blood bank laboratories. In handling "yellow-labeled" samples (which may potentially be infected) all the medical staff members have to perform their work using fume cupboards and protective clothing, gloves and facial gauze masks. Other types of samples have to be treated as if they actually did carry infectious matter; that is, much caution is required, always with the prescription that gloves must be used. In the blood donor sections of blood banks there are no such, rules. Many of the blood bank employees do handle and treat their blood samples quite "carefully" nowadays, but in view of the fact that most of the working steps are per¬ formed without gloves direct blood contact is actually possible.

It is common practice nowadays that samples are taken from the donor after the blood collecting operation, the sampling being performed in that the nurse cuts off the tube and allows the blood to flow in the open air down into sampling vials. Since these are not closed the risk of blood spilling is imminent. The blood will often splash from the vials or tube, and for this reason gloves will not always offer protection. On the other hand, it would be psychologically unattractive to treat every blood donor as a HIV-infected person, a complete set of protective clothing is therefore not recommended. Moreover such clothing if it were used would have to be exchanged entirely in everly interval from one donor to the next, so this would add a practical problem also.

Prior Art The US-A-3.523.530 discloses a blood collecting unit having a main tube provided with a cannula at one end and connected to a blood collecting vessel at its other end. A branch tube or secondary tube is further provided for taking blood samples from the donor and is connected to the main tube by means of a Y- connector. The free end of the secondary tube is provided with a needle assembly for penetrating a rubber stopper of a test tube. Clamps are arranged on the main tube on both sides of the Y- connector for directing the blood flow to either the blood collecting vessel or the branch tube. With this device it is not possible to have anticoagulant solution in the main tube and at the same time prevent it from entering the secondary tube, from which the blood samples are collected. The DE-A-2.203.858 discloses a plasmapherese unit with an infusion unit. There is no secondary tube for taking blood samples and one does not have the problem of an anticoagulant solution in the system.

The object and most important features of the invention

Therefore, an important step towards increasing the safety of working conditions will be to develop a system for safer blood sampling operations. The sampling has to be performed in a closed system where the blood will never contact the air and where the sampling vials are always closed - prior to, during and after the sampling procedure. In this manner it would be possible to avoid spilling and "splashing" of blood droplets. It is a further object to provide a device which permits the presence of anticoagulant solution in the main tube but preferably prevents the solution to enter the secondary tube and the blood sample. These and further objects have according to the invention been provided by a blood collecting unit comprising a first tube (main tube), said main tube having at one end thereof a cannula to be inserted into the vein of a blood donor and having at its other end a vessel for collecting blood from the donor, said main tube has a bifurcation situated between said cannula and vessel and provided with a second tube, so-called secondary tube, which at its outer end provides means for collecting minor amounts of blood (blood samples), which is characterized in that the secondary tube is equipped with a device preventing liquid flow through the secondary tube and constructed in such a manner that it can be opened up by being acted upon externally, so that then liquid is enabled to flow through the secondary tube.

Description of the invention

A distinctive feature of the invention is that the tube (main tube) connecting the cannula with the collector vessel has a bifurcation situated between the cannula and the vessel and provided with a second tube (secondary tube) with means at its outer end for collecting minor amounts of blood (blood samples). Also according to this feature the secondary tube end is of a construction such that it can be opened up by being acted upon externally, so that liquid is then enabled to flow through the secondary tube.

The blood collecting unit of the invention may be composed of ordinary parts such as are available for blood drawing and sampling system. Thus for instance one may employ an ordinary piece of bifurcate tubing made of plastics. For practical reasons, the bifurcation is preferably Y-shaped, with the vertical stem of the Y being directed against the direction of blood flow, i.e. towards the blood donor. The blocking device may be a so-called breakpin, that is, a tube or small pipe with a stop means lying inside the tube and destructible by being acted upon from the outside. In the preferred embodiment, the outermost end of the secondary tube has a fitting by means of which the sample collector vessel can be sealingly connected to the secondary tube. Since the sampling procedures contemplated will often comprise/taking more than one sample it is suitable for the sample collector vessel to be replaceable in a manner such that no blood can leak from the secondary tube during the replacement operation. Such systems are available commercially, although not meant for being coupled to blood collecting units. Examples of such systems are vacutainer/venoject vials consisting of glass tubes with, rubber stoppers. In the interior of the vial, the pressure is reduced as compared to ambient pressure (vacuum). Blood can be drawn into the vial in that the said stopper is perforated by means of a thin hollow needle (cannula) connected to a blood vessel. After completion of the sampling procedure the vial is removed and if desired replaced by a fresh vial, and the hole that has been made by the thin needle is sealed automatical¬ ly. The interior channel or duct of the hollow needle should be of a dimension that does not permit blood flowing therethrough unless a vacuum is applied. In one embodiment of my invention, a cannula having these properties may be connected to the outermost end of the secondary tube. The length of the main tube chosen should be in conformity with standard practice for blood collecting units. Of course other lengths may be chosen in the case of the present invention just as well as in the case of other blood collecting units in general. The main principle for choosing the position of the bifurcation point is that it should be in the upper portion of the main tube (as seen starting from the cannula) as this will facilitate the sampling procedure. The reason why the bifurcation must not be contiguous to the cannula is basically that this could all too easily cause an undesired displacement of the cannula. Therefore, in the case of most of the blood collecting units the bifurcation is to be positioned at a distance of about 22-25 cm from the cannula. The same basic principle applies to the secondary tube: Its length should be such as to permit an easy sampling operation without displacement of the cannula. At the same time, the secondary tube should be such that it can readily be removed by welding or pinching after the sampling operation has been completed. The secondary tube should therefore have a length exceeding 10 cm; if its length exceeds 35 cm this will give rise to clearly noticeable practical problems. The preferred length of the secondary tube is 12-20 cm.

As regards the position of the blocking device in the secondary tube, this will depend on whether or not a noncoagulating (nonclotting) blood sample is acceptable. If the blocking device is placed at a great distance from the bifurcation the an¬ ticoagulant collecting between the blocking device and the bifurcation may prevent clotting of the first sample. If no such sample is required this means that an unnecessary waste sample is obtained. Therefore, in one of the most practical embodiments of the invention the distance between said blocking device and bifurcation is such that only clotting samples can be collected; so that in case a nonclotting sample is actually desired the sample collector vial is provided with anticoagulant. Consequent- ly the aforesaid distance should preferably be as short as possible, as a rule less than about 2 cm (e.g. 1 cm), but at the same time allowing for easy manipulation when the blocking device is to be opened up. The most preferred embodiment of the blood collecting unit according to the invention is illustrated in Figure 1 where (1) is the cannula to be applied to the donor, (2) is the main tube, (3) is the blood collector vessel, (4) is the Y-shaped bifurca- tion provided with a blocking device (breakpin (5)), and (6) is the secondary tube provided with a fitting (7) for suitable sample receiving means. The rest of the elements shown do not form indispensable parts of the equipment but may be of practical use. (8) is a vacutainer/venoject unit comprising an adapter with a hollow needle and a vacuum tube having a rubber stopper. (9) is a cap member which is removed when the vacutainer/venoject unit is attached. (10) indicates that the main tube can be cut off by means of welding upon completion of the blood drawing operation.

Using the invention

The blood drawing procedure is started as according to current routine practice. The cannula on the blood bag tube is inserted into one of the veins of the donor. On any suitable occasion after having made sure that good blood flow and filling of the bag is being obtained one may proceed to performing the sampling operation in the following way:

An adapter (e.g. of the type having a Luer fitting at one end thereof and a thin needle at the other end) is inserted into the secondary tube fitting. Next the blocking device is opened up. A certain portion of the blood will then flow into this tube. Thereafter, when the adapter needle has been connected to a vacutainer/veno ect tube, blood is drawn into the sampling vial; and this may then be followed by a desired number of additional such vials, one after the other. After the sampling, the secondary tube is severed by welding or by being pinched off. The main blood withdrawing operation then proceeds further until it is completed.

With this method, the blood remains all the time within a closed system, with a minimum risk of direct blood contact. I have made two different embodiments of the invention. According to my type (1) embodiment the breakpin is positioned in the Y bifurcation. In my type (2) embodiment the breakpin is located close to the outermost end of the secondary tube. The blood bag tube initially contains an anticoagulant solution to prevent blood clotting in the bag.

As prescribed by law every blood portion collected must be tested in respect of hepatitis, syphilis and HIV. In order to obtain serum the samples are centrifuged. This will result in the formation of a blood clot on the bottom of the vial so that then serum (supernatant) can be sucked off therefrom for testing.

In case blood is collected in type (2) blood collecting units the blood taken for sampling will be mixed with a small amount of the anticoagulant solution from the tube. This may thwart blood clotting and obtaining of serum samples.

In type (1) blood collecting units the breakpin prevents the anticoagulant solution from spreading in the tube.

By employing the sampling method as proposed according to the invention it becomes possible for non-tested blood to be stored on closed systems all the time until cross testing takes place, and in that stage the blood has been checked and approved for transfusion.

The invention is defined in the attached claims which form an integral part of this specification.

Claims

C A I M S

1. Blood collecting unit comprising a first tube (main tube) (2), said main tube having at one end thereof a cannula (1) to be inserted into the vein of a blood donor and having at its other end a vessel (3) for collecting blood from the donor, said main tube (2) has a bifurcation situated between said cannula and vessel and provided with a second tube, so-called secondary tube (6), which at its outer end provides means for collecting minor amounts of blood (blood samples), c h a r a c t e r i z e d i n, that the secondary tube (6) is equipped with a device (5) preventing liquid flow through the secondary tube and constructed in such a manner that it can be opened up by being acted upon externally, so that then liquid is enabled to flow through the secondary tube.

2. Blood collecting unit according to claim 1, c h a r a c t e r i z e d i n, that the device (5) preventing flow through the secondary tube (6) is positioned at a distance of less that 2 cm from the bifurcation.

3. Blood collecting unit according to claim 2, c h a r a c t e r i z e d i n, that the position of said device (5) is contiguous to the bifurcation.

4. Blood collecting unit according to any of claims 1-3, c h a r a c t e r i z e d i n, that said device is a breakpin (5) arranged within the secondary tube (6).

5. Blood collecting unit according to any of the preceding claims c h a r a c t e r i z e d i , that the free end of the secondary tube (6) is provided with a fitting (7) for connection to a blood sampling unit, such as a vacutainer/venoject unit (8) .

6. Use of the blood collecting device according to any of claims 1-4 for taking blood samples from a donor whose blood is being drawn off in a closed system.