Non-reopening locking pinch clamp for tubing

A tube clamp having first and second opposed jaws (1012, 1014) joined by a hinge (1016), the jaws (1012, 1014) movable between open and closed positions, the tube clamp adapted to attach to a flexible plastic tube (1024) so that the tube (1024) passes between the jaws (1012, 1014), whereby the flow of fluid through the tube (1024) is permitted when the jaws are open but is blocked when the jaws are brought together to the closed position to pinch closed the tube there-between, and locking means (1048,1036,1042) to effect substantially permanent and irreversible locking of the jaws (1012, 1014) in the closed position.

TECHNICAL FIELD

This invention relates principally to pinch clamps for flexible tubing and, particularly though not exclusively, to one-piece molded-plastic tube clamps for use in medical procedures such as the collection or administration of intravenous (IV) liquids where it is important to permanently lock the clamp so as to securely and permanently close a tube.

However, the present invention may be applied more widely than tube clamps because the means by which permanent locking of a tube clamp can be achieved in accordance with this invention is applicable to other devices, whether for medical use or otherwise.

BACKGROUND

In our prior international patent application PCT/AU99/00918 relating to “Sampling in Blood Collection”, we disclosed valve means whereby the first portion of blood collected from a donor could be diverted for sampling before the blood line was connected to the blood collection pouch. An important feature of such valve means is that, once sufficient blood has been diverted for samples, connection to the diversion tube must be permanently closed to be absolutely sure that no contamination from the diversion tube can find its way into the blood collection line to the collection pouch. The valve means disclosed in our prior application was fool-proof in the sense that the collection line could not be opened before the diversion line had been securely closed and that, once closed, the diversion line could not be re-opened or re-connected. This arrangement allowed samples to be drawn off from the diversion line using a sample port and vacuum vial before blood collection commenced.

An important reason for wishing to divert blood for sampling during blood collection is that any skin plug that is cut and retained by the needle can be washed out into the diversion or sample line rather than into the main collection pouch. It is thought that such skin plugs are responsible for much of the bacterial contamination of collected blood pouches.

In an alternative method of ‘sampling first’, the initial flow of blood is diverted to a sealed sample bag while the blood line to the collection pouch is temporarily blocked, after sufficient sample blood has been collected, the tube to the sample bag is blocked and the tube to the pouch is opened. If desired, samples can be drawn off from the sample bag while blood collection continues. This system is not fool-proof in that manual clamps are used to block the diversion tube and the main blood line. They can be operated in the wrong sequence or the clamp on the diversion line can either be re-opened or not properly closed.

In the collection of blood from donors, or when handling blood or other IV liquids in flexible tubing, one-piece molded-plastic pinch clamps are often used to control fluid flow in the tubes because they are cheap and disposable. In some such situations it is important that the clamps cannot be re-opened after having been finally closed to seal a tube.

The tube clamp with which the present invention is concerned is of the type that comprises a one-piece generally C-shape plastic molding having a pair of opposed jaws joined by a flexible hinge portion and that is adapted to fit onto a flexible plastic tube so that the tube passes between the jaws, whereby the flow of fluid through the tube is permitted when the jaws are open but is blocked when the jaws are brought together to pinch close the tube there-between. This type of tube clamp normally includes releasable locking means that allows the jaws to be clipped together in the closed position.

In blood collection procedures where many donors and blood packs are handled by a single phlebotomist in an hour, it is also important that the clamp be easy to lock closed, that any locking tabs or the like do not protrude so as to be likely to tear or puncture surgical gloves, poke into the user's thumb or fingers or to snag medical dressings, clothing or other fabric. It is also desirable that there is auditory and/or visual confirmation of proper closure. Preferred embodiments of the invention provide a device that satisfies at least some, if not all, of these requirements.

OUTLINE OF THE INVENTION

The present invention involves a non-reopening tube clamp suitable for use on medical tubing, such as the sample diversion tube of a ‘sample first’ blood collection system. However, the non-reopening clamp can be used with many other situations where the permanent blocking of a flexible intact tube is necessary.

From one aspect, the tube clamp comprises a one-piece generally C-shape plastic molding that is adapted, in its open position, to permit fluid flow through a flexible-walled tube and, in the closed position, to compress and block fluid flow through the tube. The clamp has first and second jaw portions that are spaced apart when the clamp is in its open position and are brought together when the clamp is in its closed position. It has locking means for permanently securing the jaw portions together in the closed position and first and second compressing means adapted to compress the tube between them when the clamp is in the closed position. Apertures are formed in the clamp through which a tube may be threaded so as to guide the tube within the clamp between the first and second compressing means that form part of the respective jaw portions. Preferably, the apertures have closed peripheries so that a tube passed through the apertures cannot be removed except by pulling the tube right through the clamp. After manufacture and assembly, this will generally be prevented by end fittings attached to the tube.

The first and second compressing means are adapted to contact and compress a tube between them when the clamp is in the locked position.

Preferably, the compressing means are substantially linear, thus forming the first and second compressing edges. The edges may be misaligned with one another in the axial direction of the tube so that the tube is subject to both compression and shear when the clamp is in the closed position. This has the advantage that less force is required to close the clamp because the compressing means do not hit head-on but are slightly displaced axially with respect to the axis of the tube.

It is also advantageous to form small teeth on at least one of the compressing edges. The teeth are generally of the same size and spaced periodically. The teeth are usually rounded to prevent puncturing of the tube. If the teeth are formed on both of the compressing edges, the teeth on each edge are spaced to allow locating of the teeth of the first edge in the spaces between the teeth of the second edge when the clamp is in the closed position.

The invention provides for a groove formed in at least one of the compressing edges. The invention provides for rounded or prismoidal grooving.

In one arrangement, one compressing edge is grooved (concave edge) and another is not grooved (convex edge); the concave and convex shapes are adapted such that the concave edge locates the convex edge (with the tube therebetween) when the clamp is in the closed position. The invention provides for different geometries of the concave and the convex edges, including cylindrical and prismoidal. The geometry and dimensions of the concave edge may be different from that of the convex edge. These differences allow for the combined action of the compression and shear forces that arise during the locking action, thus resulting in better blocking of the tube.

The locking means may comprise at least two hook-like tabs that engage a corresponding locking hole or holes on the other. Usually, the outer portion of the locking hole is recessed so that the hook-like tabs on the other portion lies within the recess to thereby inhibit access to the hook when the clamp is in the closed position and is locked by the engagement of the hook-like tab within the locking hole.

Preferably, the locking means comprise first and second hook-like tabs and corresponding first and second holes.

In one arrangement both first and second hook-like tabs are formed on one end of the clamp, whereby the corresponding first and second holes are formed on the other end of the clamp.

In another arrangement the first hook-like tab is formed on one end of the clamp, whereby the second hook-like tab is formed on the other.

Further, the invention provides for Locking means comprising a block and a hook-like tab and two holes: one to accommodate the block and another to accommodate the hook-like tab. In one arrangement both the block and the hook-like tab are on the same end of the clamp. The block has a preferably blunt end to prevent an injury to an operator.

The dimensions of the block and the corresponding hole are adjusted so as to allow the block to snugly fit into the said hole with only a minimal space left between the block and the sides of the hole, thus restricting the movement of the block (and thus the movement of a hook-like tab within the corresponding locking hole) at least in the longitudinal direction (with the clamp being in the locked position) to prevent the clamp from being unintentionally unlocked.

In some arrangements it is preferable to have the transverse dimension of the block larger than the transverse dimension of the hook-like tub.

It is understood in this invention that there may be many variations of the shape and size of the block and the corresponding hole.

From another aspect, the present invention comprises a tube clamp of the type indicated wherein the locking means, when activated, effects substantially permanent and irreversible locking of the jaws in the closed position. Preferably, the locking means comprises a T-shape stud integrally molded with one jaw and a corresponding slot in the other jaw positioned and adapted to accept the stud, the slot being proportioned so that the head of the T-stud can be forced through the slot by folding its sides inwards towards the leg of the T-stud and so that, after passing through the slot, the head of the T-stud is enabled to spring outwards to lock the jaws together. For convenience, it will be said that the T-stud enters the slot from the proximal side and protrudes therefrom on the distal side.

From another aspect, a preferred feature of the above-described locking means is the provision of a recess on the distal side of the slot adapted to accommodate the head of the T-stud so that its distal face does not protrude substantially beyond the distal surface of the jaw in which the slot and recess are formed. A further preferred feature of the locking means is ensuring that the lateral dimension of the recess is somewhat less than the width of the head of the T-stud, when flattened out. In other words, the head of the T-stud will be neatly accommodated by the recess when it is bent or domed so as to be distally convex. Thus, the opening force exerted by the pressure on the closed tube, or by a person's attempt to re-open the clamp, will tend to flatten the head of the T-stud and to jam it lengthwise in the recess so that it will be most difficult to invert and pull through.

We have found that this T-stud design of permanent locking means has the remarkable feature that it is easy to close but very difficult to re-open, unlike most hook and slot locking fasteners where the locking force is commensurate with the unlocking force. By molding the head of the T-stud to be slightly domed, it can be made self-aligning with the slot for even greater ease of entry. Moreover, the slightly domed external (distal) face of the T-stud engaged in the recess presents no protrusion that is likely to snag dressings, puncture surgical gloves or indent the fingers of users. This combination of features allows a phlebotomist to lock many clamps on tubes in a short space of time without tiring or repetitive strain injury.

From another and more general aspect of this invention, the permanent locking means indicated above (i.e., the use of a domed T-stud cooperating with a recessed slot) may be applied to a variety of other devices, especially those for use in the medical field where the properties of ease of closure, smoothness of finish and permanency of closure are important. Examples are patient identification wrist bands and tags, tags for sample or disposal bags, closures for sharps containers and dangerous waste.

Clamp210of the first example shown inFIGS. 1-6is a unitary plastic injection molding of a flexible and resilient polymeric material such as polypropylene. It is of a generally C-shape and also comprises two opposed relatively stiff jaws212and214, a central relatively flexible hinge portion216that joins the jaws together and locking means218comprising a first latch portion220formed as an extension of jaw214and a second latch portion222formed in the end of jaw212. First latch portion220comprises a necked tab226with shoulders227, while second latch portion222comprises a pair of spaced hooks223that are adapted to snap fit around the neck of tab226and over shoulders227to permanently lock clamp210closed (when jaws212and214are firmly pushed together).

A central aperture228is formed in hinge portion216and a second aperture230of similar size is formed in jaw212, holes228and230allowing a flexible tube232to be threaded through them so as to be captured by clamp210.

An inwardly extending abutment234is formed on the inner face of jaw212and a similar opposing abutment236is formed on the inner face of jaw214, abutment234having an inner laterally extending compressing edge238and abutment236having an opposing lateral extending compressing edge240. In this example, however, edges236and238are rounded and cylindrical in shape to better engage and pinch tube232between them upon closure of clamp210.

In operation, after tube232has been threaded through apertures228and230of the open clamp so as to lie between compressing edges238and240, as shown inFIG. 5, fluid is free to flow through the tube although tube232passes between compressing edges238and240and is held in that position by apertures228and230. To close clamp210and securely cut off fluid flow through tube232, jaws212and214are pressed together until latch portions220and220engage and lock together. This action brings compressing edges238and240to bear forcibly on tube232and to subject the tube to a compressive force so as to be pinched closed.

Compressing edges of the second example are schematically presented inFIG. 7. In this arrangement the first compressing edge338is of concave prismoidal shape and is adapted to locate the second convex rounded edge340when the clamp is in the closed position, thus blocking a pipe332by combined action of compression a shear forces.

Compressing edges of the third example are schematically presented inFIG. 8. In this arrangement the first compressing edge438is of concave rounded shape and is adapted to locate the second convex prismoidal edge440when the clamp is in the closed position, thus blocking a pipe432by combined action of compressing a shear forces.

Compressing edges of the fourth example are schematically presented inFIG. 9. In this arrangement the first compressing edge538is of concave prismoidal shape and is adapted to locate the second convex prismoidal edge540when the clamp is in the closed position, thus blocking a pipe532by combined action of compressing a shear forces.

Compressing means of the fifth example are schematically presented inFIG. 10. In this arrangement small teeth650are formed on both first compressing edge638and second compressing edge640. The teeth ensure complete blocking a tube642when the clamp is in the closed position.

Clamp810of the sixth example shown inFIGS. 11-12is also a unitary plastic injection molding. It comprises two opposed jaws812and814, a central relatively flexible hinge portion816that joins the jaws together and locking means818comprising a hook portion820formed as an extension of jaw812and an eye portion822formed in the end of jaw814and having first hole824adapted to snugly accommodate the first barbed end tab826of hook portion820and second hole825adapted to snugly accommodate the second barbed end tab827of hook portion820. A first aperture828is formed in hinge portion816, a second aperture830and third aperture831of similar size are both formed in hook portion820, apertures828,830and831are allowing a flexible tube (not shown) to be threaded through them so as to be captured by clamp810. Ribs850are formed on external faces of jaws812and814to ensure good grip with fingers of an operator.

An inwardly extending prismoidal abutment834is formed on the inner face of jaw812and a similar opposing abutment836is formed on the inner face of jaw814, abutment834having an inner compressing edge838and abutment836having an inner compressing edge840that are approximately opposite each other when the clamp is in the open position, as inFIG. 11.

In operation, after tube (not shown) has been threaded through apertures828,830and831of the open clamp so as to lie between compressing edges838and840, fluid is free to flow through the tube although the tube passes between compressing edges838and840and is held in that position by apertures828,830and831. To close clamp810and securely cut off fluid flow through the tube, jaws812and814are pressed together by applying compression force to their external faces and utilizing ribs850until the barbed tabs826and827of hook portion720enter corresponding holes824and825of eye portion822and snap in place. This action brings abutment edges838and840to bear forcibly on the tube and to subject the tube to a compressive force, thus completely blocking the tube. Implementation of two hooks in this example ensures firm locking of the clamp and makes the closed position practically non-unlockable.

Clamp910of the seventh example shown inFIGS. 13-14is also a unitary plastic injection molding. It comprises two opposed jaws912and914, a central relatively flexible hinge portion916that joins the jaws together and locking means918comprising a hook portion920(in this example comprising a single barbed end tab927and a block926) formed as an extension of jaw912, and an eye portion922formed in the end of jaw914and having a guiding hole924adapted to accommodate the block926of hook portion920and a locking hole925adapted to snugly accommodate the barbed end tab927of hook portion920. The block926is an extension of the hook portion920of the jaw912, the said block having a preferably blunt end that is not limited in shape to that shown inFIGS. 13-14. The guiding hole924of the jaw914has dimensions sufficient to allow sliding insertion of the block926but small enough to prevent or at least significantly restrict the displacement of the said block within the hole924in longitudinal direction of the jaw914, so that the overall distance, in the longitudinal direction of the jaw914, between the walls of the hole924and the block926inserted therein is smaller than the overall distance, in longitudinal direction of the jaw914, between the barbed tab927and the walls of the second hole925with the said barbed tab inserted therein. A first aperture928is formed in hinge portion916, a second aperture930and third aperture931of similar size are both formed in hook portion920, apertures928,930and931are allowing a flexible tube (not shown) to be threaded through them so as to be captured by clamp910. Ribs950are formed on external faces of jaws912and914to ensure good grip with fingers of an operator.

An inwardly extending prismoidal abutment934is formed on the inner face of jaw912and a similar opposing abutment936is formed on the inner face of jaw914, abutment934having an inner compressing edge938and abutment936having an inner compressing edge940that are approximately opposite each other when the clamp is in the open position, as inFIG. 13.

In operation, after tube (not shown) has been threaded through apertures928,930and931of the open clamp so as to lie between compressing edges938and940, fluid is free to flow through the tube although the tube passes between compressing edges938and940and is held in that position by apertures928,930and931. To close clamp910and securely cut off fluid flow through the tube, jaws912and914are pressed together by applying compression force to their external faces and utilizing ribs950until the block926and the barbed end tab927of hook portion920enter corresponding hole924and hole925of eye portion922and the tab927snaps in place. This action brings abutment edges938and940to bear forcibly on the tube and to subject the tube to a compressive force, thus completely blocking the tube. The block926restricts relative longitudinal movement of the two jaws, thus preventing disengagement of the hook and, therefore, accidental unlocking of the clamp.

Clamp1000of the eighth example shown inFIGS. 15 to 18is a unitary plastic injection molding of a flexible and resilient polymeric material such as polypropylene or PVC. It is of a generally C-shape and, for the sake of description, can be divided into three portions; namely two opposed relatively stiff jaws1012and1014, a central relatively flexible hinge portion1016that joins the jaws together and locking means1018comprising a T-stud male element1020formed as an extension of jaw1014and a female slot element1022formed in the end of jaw1012. A flexible plastic tube1024(shown in broken lines) can be threaded longitudinally through clamp1000and so that it passes between inwardly-facing wedge-shape abutments1026and1028that form part of jaws1012and1014(respectively). Accommodation of tube1024is achieved by three longitudinally aligned apertures in clamp1000, one (1030) in hinge portion1016and two (1032and1034) in jaw1014. This method of accommodating tubing in one-piece pinch clamps is well known in the art.

As best seen fromFIG. 17A, T-stud element1020is molded integrally with the end of jaw1014to be up-standing therefrom and to have a leg1036that supports a domed head1038with significant longitudinal dimension. Head1038also has significant lateral dimension, as will also be seen from the external perspective views ofFIGS. 15 and 16. The underside of head1038is recessed or grooved so as to have areas1040of reduced cross-section and greater flexibility.

It will also be seen fromFIGS. 15 and 17Athat slot element1022comprises a distal entry slot1042that opens out into a proximal recess1044that is formed so as to provide shoulder abutments1046for locating the ends1048of T-stud1020.

Referring toFIGS. 16,18A and18B, which show clamp1000in the locked-closed position, it will be seen that head1038of T-stud1020is substantially entirely housed within recess1044of slot element1022and the ends1048of T-stud1020are wedged against shoulders1046of the recess, making withdrawal extremely difficult, Indeed, we have found with the design depicted that forcing jaws1012and1014apart cannot be done by the fingers of a normal person, instead requiring tools and a force of some kilograms that results in snapping leg1036rather than the inversion of head1038.

The ninth example, shown inFIGS. 19 to 20, comprises a clamp1100that is very similar to clamp1000of the eighth example, except that the clamping means has been inverted so that T-stud1120now depends from jaw1112and recessed slot1122is formed in jaw1114so that the head1138enters the hollow1150. This arrangement ensures that head1138is well out of the way and, indeed, will be very difficult to access if it was intended to use some tool to manipulate the head to open the clamp.

Thus, apart from its inversion, the locking means operates essentially the same way as in the eighth example.

The tenth example ofFIGS. 21A to 21Dcomprises a clamp1200that is very similar to clamp1000of the eighth example. The tenth example differs from that of the eighth example in that the aperture1222is provided with a chamfered surface1224on the distal side nearer to the hinge. The recess1044still has shoulder abutments1046that the ends1048overlie and engage when the clamp1200is closed.

The purpose of the chamfered surface1224is to allow the lower leg1202A to pass though the aperture1044and spring outwards substantially at the same time as the upper leg1202B. This is apparent inFIG. 19C, where the clamp is almost closed and the two legs1202A & B are still just engaging the sides1204A &1204B of the aperture. Further movement results in the lower leg1202A being able to swing outwards across surface1224whilst upper leg1202B swing outwards across shoulder1046substantially simultaneously.

This results in both legs locking at substantially the same time and producing a single audible “click”. In the eighth and ninth examples the upper leg clears the aperture before the lower leg and this can result in two separate audible “clicks”. If the user does not push hard enough the upper leg releases and produces a click. The user may think the clamp is engaged fully and not continue pushing to engage the lower leg. The tenth example overcomes these disadvantages.

The head of the eighth to tenth examples comprises two arms that extend from the central leg,1036,1120and1226respectively in opposite directions to each other. The head may comprise more than two arms, such as three, four or more arms extending radially from the central leg, preferably spaced circumferentially equally from each other.

The head need not be formed of discrete arms. Another alternative is a domed head having a substantially continuous surface. Examples of suitable surfaces include all or part of a cone, a frusto-conical annular flange and part of an ellipsoid.

Clamp1300of the eleventh example shown inFIGS. 22 to 25is similar to the example ofFIGS. 15 to 18Band is a unitary plastic injection molding of a flexible and resilient polymeric material such as polypropylene or PVC. It is of a generally C-shape and, for the sake of description, can be divided into three portions; namely two opposed relatively stiff jaws1312and1314, a central relatively flexible hinge portion1316that joins the jaws together and locking means1318comprising a stud male element1320formed as an extension of jaw1314and a female slot element1322formed in the end of jaw1312. A flexible plastic tube (not shown) can be threaded longitudinally through clamp1300and so that it passes between inwardly-facing wedge-shape abutments1326and1328that form part of jaws1312and1314(respectively). Accommodation of tube is achieved by three longitudinally aligned apertures in clamp1300, one (1330) in hinge portion1316and two (1332and1334) in jaw1314.

As best seen fromFIG. 22A, stud element1320is molded integrally with the end of jaw1314to be up-standing therefrom and to have a leg1336that supports a domed head1338. The head1338is continuous and is in the form of a truncated cone. The underside of head1338is recessed or grooved so as to have areas1340of reduced cross-section and greater flexibility. This allows the cone shaped wall1339to deflect as needed

It will also be seen fromFIG. 23that slot element1322comprises a distal entry slot1342that opens out into a proximal recess1344that is formed so as to provide shoulder abutments1346for locating the peripheral edge1348of wall1339.

Referring toFIGS. 24 and 25, which show clamp1300in the locked-closed position, it will be seen that head1338of stud1320is substantially entirely housed within recess1344of slot element1322and the peripheral edge1348of stud1320is wedged against shoulders1346of the recess, making withdrawal extremely difficult.

To aid insertion, the recess1322may have a chamfered surface1324as with the example.

Whilst the eleventh example has a generally rectangular slot1322, the slot1322may be made circular to better fit with the head1338.

Whilst the head1338has a continuous wall1339, if needed one or more slots may be placed in the wall1339to provide sufficient flexibility.

While eleven examples have been described and illustrated, it will be appreciated that many changes to the examples can be made without departing from the scope of the present invention as outlined above.