Couplings

Abstract

A coupling, particularly for blood-processing sets, is shown which permits the assembly of a "kit of parts" of such a set by a user not under special conditions of sterility. This is achieved by terminating the items of the kit e.g. bags and tubes in frangible diaphragms and joining the items by means of a solvent for the material of the diaphragms so that they are unified together. They may then be ruptured to open up a fluid path through the items. Sleeves surrounding the diaphragms are preferably also unified together by the same solvent. By the formation of such a solid layer of the material of the diaphragms between them and uniting them, ingress of contaminants from the previously exposed faces of the diaphragms when the diaphragms are ruptured is hindered or prevented.

Description

FIELD OF THE INVENTION

This invention relates to couplings used in the medical and research contexts.

BACKGROUND OF THE INVENTION

In these uses, couplings have to be made between elements such as bags and tubes to establish a fluid flow path of a particular character, without however exposing the interior of the coupling or the other elements or the fluid to harm, e.g. by infection by harmful microorganisms, or by other entrapped contamination such as chemical contaminants.

A particular area in which the problem presents great difficulties is that of blood transfusion and in particular in the handling and the fractionation of blood once it has been received from the donor.

For this fractionation, the blood is treated by various methods most of which include centrifuging and freezing in an array of three or even more bags linked to each other by closable tubes. A first separation is done in the first bag and one of the fractions is pressed from that bag into a second where a further operation is carried out and then a fraction from the second bag is returned either to the first or to a third bag and so on.

The interior of all these bags and of the tubes linking them have to be absolutely sterile. These bag sets have always been pre-assembled, the whole of the pre-assembly being done under sterile conditions in the factory and the whole of the assembly being sent out as a sealed unit to where it is to be used. The bags containing the various fractions can only be separated by once for all destruction of the assembly, which is usually carried out by a heat sealing of the tube.

This system has obvious disadvantages namely that a large number of different types and sizes of bag sets have to be assembled in the factory and cannot thereafter be altered. Also the user has to hold a large stock of different sorts of bag sets according to all the sorts of operations he may want to perform. Attempts have therefore been made to provide a kit wherein there would be provided sterile closed bags preferably only of one or two sizes and tubes preferably only of a few lengths, any of which may be joined together by the user in any desired combination. The difficulty with such a system is the need for sterility in the couplings and it is to this problem that we direct our attention.

In one proposal for dealing with this difficulty in German Auslegeschrift No. 1300635 it is proposed to have both the male and the female parts of the coupling closed by a diaphragm so that the interior of the bag or the tube as the case may be is kept sterile, the two parts of the coupling being forced together in a bath of disinfectant. An internal tube is then used to pierce the diaphragms, which in the assembled state of the coupling lie face to face, and establish a fluid path through the coupling. The coupling remains assembled only because of the tight fit together of the parts -- there is nothing additional holding it together. The coupling is assembled in a disinfectant bath because if microorganisms are trapped between the parts of the coupling and in particular between the diaphragms they may pass into the fluid stream or may even be driven into it by the needle when that pushes through the diaphragms. Clearly it is not desirable that one should have to do the actions of forming the coupling under the surface of a bath.

SUMMARY OF THE INVENTION

In the present invention we provide a coupling for medical or research equipment, for example blood transfusion processing apparatus, wherein elements coupled together are sealed off by penetratable diaphragms one diaphragm being associated with each part of the coupling, the two diaphragms being unified together face to face by a solvent for the material of the diaphragms, and an internal means within the coupling for penetrating through the diaphragms when unified together. We find that as a result (1) micro-organisms on the respective outer faces of the diaphragms are frequently rendered non-viable by the effect of the solvent (2) that any living micro-organisms which may survive this treatment, or any other harmful contaminants, are in effect locked into the solid solution of diaphragm material which is formed between the diaphragms when they are unified by the solvent, and (3) we provide a positive means (other than a mere push fit) for holding the coupling assembled viz the unification together of the material of the diaphragms. Suitably the coupling includes male and female sleeves surrounding the diaphragm and forming a push-fit together, and the solvent for the material of the diaphragms is also a solvent for the sleeve parts and is applied between them whereby the coupling parts are unified over substantially the whole of the interacting surfaces of the sleeves and the diaphragms.

In another aspect of the invention we provide equipment for the handling of fluid which consists of at least two bags connected together by at least one tube, a coupling between the tube and at least one of the bags including diaphragms unified by a solvent for the material of the diaphragms, the diaphragms respectively forming a barrier to access to the tubes and to the at least one of the bags, and means inside the coupling for penetrating the diaphragms when sealed together to open up a fluid path from the at least one bag to the tube.

It is an advantage of the coupling and of the system that it can be used not only for assembly by the user of a set of bags to suit his own requirements without having to work under the surface of a bath of disinfectant but can also be used within the factory for sending out pre-assembled bag sets to those who want them, without the need for setting up in the factory a completely sterile zone for the assembly.

In the accompanying drawings:

FIG. 1 illustrates schematically a prior art arrangement of bag set,

FIG. 2 illustrates schematically a bag set embodying the present invention,

FIG. 3 shows, a male element and FIG. 4 a female element of the coupling embodying the invention, both in a diametrical section,

FIG. 5 shows, in a larger scale the elements assembled and with diaphragms unified together, and

FIG. 6 illustrates how a fluid path is opened through the unified diaphragms.

In FIG. 1 of the drawing we show a prior art bag set consisting of bags a, b and c, which are interlinked respectively by tubes 1 and 2 each having socket parts 3 on their ends fitting over plugs extending from the bags a, b, and c. The sockets 3 may be glued onto the plugs. Each of these tubes is open ended at each end as are also the plugs of the bags so that sterility of the whole assembly is achieved only by sterilisation of the component parts and their assembly together into a sealed set all under sterile conditions. It is obvious the set cannot be dis-assembled in any way while maintaining sterility, except destructively (the method usually used being sealing-off tubes 1 or 2 by heating them and then cutting them beyond the seal).

In FIG. 2 we show elements of a bag set embodying the present invention. The bags a', b' and c' each have at least two female socket elements 5 embodying the invention incorporating as they do each a diaphragm preventing access of micro-organisms to the interior of the bags. They will be described in more detail later. An inlet 6 to the first bag a' is shown wherein for example blood from a donor may be first introduced into the bag set. This connection may be one according to the invention or may be a conventional one. Each of the bags has a plug 7 which may be one element of a coupling according to the invention or may be a known type of plug with a tear-off seal to allow access to the final contents of the bag when they are to be used. These bags may be sent out from the factory as they are in sterile and sealed condition to the user. They may be all the same size as is shown here or may be of a range of sizes which rationally should include only two sizes and not more. Since the bags are totally sealed they cannot be sterilised by ordinary heat treatment since they contain air and may contain for example anti-coagulants, and they are therefore sterilised by irradiation preferably by gamma rays. Also making up part of the bag set are tubes such as 8 which have at each end a male element 9 for the coupling embodying the invention. Any of the male elements 9 will fit any of the female elements 5 on any of the bags a' to c' and thus the user may assemble with the bags and with the tubes he is given a set of bags which is uniquely adapted to his own requirements. Each of the male elements 9, which will be described in more detail later, contains a diaphragm sealing off the interior of the tube to the outside atmosphere and the tubes are sent out in internally sterile condition having been sterilised by irradiation again preferably by irradiation with gamma rays.

The assembly together of the male and female elements of the coupling will now be described more particularly with reference to FIGS. 3 to 6. FIG. 4 also shows how the female socket elements need not necessarily be integral with bags but may form the end fitting of a tube. It is equally possible that the male elements 9 may be integral with the bags.

The female socket part 5 has a sleeve at 10 across which is formed a diaphragm 11. The sleeve is integral with a fitting 12 for receiving the end of a tube 8' as shown in FIG. 4 or the sleeve 10 may be moulded integrally with a bag. The male element 9 is sealed off by a diaphragm 13 at the axially outer end of a sleeve 14 of which the outer diameter is such that the sleeves 14 and 10 are a tight push-fit together. A bellows construction 15 allows for relative axial movement of the sleeve 14 and another sleeve 16 of similar diameter at the other end of the bellows. This sleeve 16 constitutes a fitting in which the end of a tube such as 8 is securely fixed. In it there is also positioned an annular collar 17 which is a base for a hollow needle 18 which extends axially from that base within the sleeve 16 to within the sleeve 14 and presents a sharp point 19 towards the diaphragm 13. When the bellows construction is in its relaxed condition as shown in FIG. 3 the needle point 19 is clear of the diaphragm 13. As best seen in FIG. 5 the needle 18 has a pair of ports 20 near its pointed end so there may be fluid communication from that pointed end through the hollow needle and the collar 17 into the tube 8.

Preferably all the parts mentioned including the needle are formed of plastics material although the needle may of course be of metal. A preferred material for the plastics is a polyvinyl chloride material since this is cheap, readily workable and not difficult to sterilise.

A solvent particularly suitable for use with polyvinyl chloride is cyclohexanone since this has, incidentally, an appreciable sterilizing effect of its own.

To assemble the coupling together all that the user has to do is to coat the outer surface of one or preferably both diaphragms with an ample coating of a solvent for the material of those diaphragms. Obviously from the commercial point of view it would be desirable to make both diaphragms of the same material so that the widest range of solvents is available but obviously the diaphragms could be of different materials, and then a common solvent or else a solvent mixture would have to be used. The diaphragms are then pressed together face to face and left until the joint has solidifed. It would be preferable again that the material of the diaphragms should be the same as that of the sleeves 10 and 14 and then the same solvent may be also used between the touching surfaces of the sleeves and a unified joint may be formed overall to give mechanical strength to the seal. The layer 21 in FIG. 4 between the diaphragms is a solid layer of material common to each diaphragm while layer 22 is made up of material common to the sleeves 10 and 14. Any micro-organisms on the formerly exposed outer surfaces of the diaphragms are locked into the solid joint formed between the diaphragms by the layer 21 and when the needle 18 is pushed through the diaphragms so as to establish a fluid path through the coupling there is a statistically negligible risk that any viable micro-organisms will be introduced into that flow path. The needle may remain penetrating the diaphragms so that the ports 20 remain beyond the diaphragms and fluid issues from them beyond the diaphragms, or may be withdrawn again so that the hole that it has pierced through the diaphragms is used for the passage of fluid.

Obviously, the assembly step of the coupling need not be done under sterile conditions, the only precaution necessary being that a complete and adequate coating of solvent material is applied to the faces of the diaphragms.

The reduction in the risk of infection resulting from the use of this coupling and this bag system is particularly valuable when the long term storage of blood or blood fractions is being considered.

The internal penetrating elements may be attached to a bellows on as female socket element rather on a male, as shown here, or may be entirely loose within either element of the coupling (cf German Auslegeschrift No. 1300635).

Claims

What I claim is:

1. Equipment for the handling of fluid which comprises at least two bags connected together by at least one tube, a coupling between the tube and at least one of the bags including diaphragms unified by a solvent for the material of the diaphragms, the diaphragms respectively forming a barrier to access to the tubes and to the at least one of the bags, and means inside the coupling for penetrating the diaphragms when sealed together to open up a fluid path from the at least one bag to the tube.

2. Equipment as claimed in claim 1 wherein the coupling includes male and female sleeves surrounding the respective diaphragms and forming a push-fit together, the coupling parts being unified over substantially the whole of the interacting surfaces of the sleeves and the diaphragm by a resolidified region of their respective materials.

3. Equipment as claimed in claim 2 wherein the diaphragms and sleeves are all made of polyvinyl chloride.

4. Equipment as claimed in claim 2 wherein the said coupling includes an axially compressible bellows intermediate at least one tube and the diaphragms and the said means inside the coupling includes a needle mounted within the bellows with one end presented towards the diaphragm and one anchored to the end of the bellows remote from the diaphragm, whereby axial compression of the bellows can drive the needle through the diaphragm.

5. Equipment as claimed in claim 4 wherein all of the said sleeves, diaphragms and bellows are made of polyvinyl chloride.

6. A modular coupled equipment system comprising a plurality of items of medical or research equipment sealingly attached together in temporarily nonintercommunicating manner, and adapted to be made intercommunicating for use, comprising a plurality of coupled-together sets of individual coupling elements and respective items of equipment, each set comprising a coupling element and an item of equipment attached thereto, each coupling element comprising a housing, and a coupling passage extending through the housing and open at each end, the coupling element being attached to the item of equipment so that one open end of the coupling passage communicates with the item of equipment; a penetrable diaphragm disposed across the coupling passage and sealing off the passage from flow therethrough until penetrated; the housing of each coupling element at the other open end of the passage being shaped to sealingly interconnect with the coupling element of another set to which it is sealingly attached, the coupling passages of interconnected coupling elements being aligned to form an intercommunicating through passage extending to each item of equipment closed off by the diaphragm in the coupling passages; the diaphragms of adjacent coupling elements being in abutting relation and united by an intermediate layer of interdiffused diaphragm material, and disposed in at least one of each two adjacent coupling elements at least one internal means for each pair of diaphragms for penetration through the diaphragms thereof to provide intercommunication between the coupled items of equipment via the passage.

7. A modular coupled equipment system according to claim 6 wherein the interconnected coupling components comprise interconnected male and female sleeves surrounding the respective diaphragms and forming a push-fit together, the coupling components being united over substantially the whole of the abutting surfaces of the sleeves and the diaphragms by interdiffusion of diaphragm material.

8. A modular coupled equipment system according to claim 6 wherein the diaphragms and the sleeves are all made of plastic material.

9. A modular coupled equipment system according to claim 8 wherein the plastic material is polyvinyl chloride.

10. A modular coupled equipment system according to claim 6 wherein the diaphragms are made of plastic material.

11. A modular coupled equipment system according to claim 6 wherein the said internal means includes an axially compressible bellows, a needle mounted within the bellows with one end presented towards the diaphragm and one anchored to the end of the bellows remote from the diaphragm, whereby axial compression of the bellows can drive the needle through the diaphragm.

12. A modular coupled equipment system according to claim 11 wherein all of the said sleeves, diaphragms and bellows are made of polyvinyl chloride.

13. A modular coupled equipment system according to claim 11 wherein the needle is hollow and has fluid ports opening to its outside near the end presented towards the diaphragm.

14. Coupling elements for a coupling according to claim 6.

15. Method of coupling together respective coupling elements on respective items of equipment to be coupled together, each coupling element having a penetratable diaphragm preventing access to the interior of the item from the outside, and at least one of the elements having internal means for penetrating through the diaphragms, which comprises applying a solvent to the exposed faces of the diaphragms to form a solution of their material at the said faces and bringing the said faces into face-to-face contact whereby to unify the diaphragms by a layer of their material.

16. Method according to claim 15 wherein the said material is polyvinyl chloride and the solvent is cyclohexanone.