GB2368624A - Check valve formed from a single sheet of folded material - Google Patents

Abstract

A unidirectional valve 1, suitable for use in a cannula or other medical equipment, is formed from a single sheet of material, such as polyethylene, having an outer profile cut to shape and having fold lines 16,18,34 defining triangular sections 26,28,30. When fully folded, the valve 1 has a polygonal circumferential shape and can be located within a cannula; opened upon the insertion of a needle 64 and closed upon removal of the needle 64 by a combination of the resilience of the valve material and the back pressure acting on the valve.

Description

A Valve

Field of the Invention The present invention relates to valves, in particular although not exclusively, to a valves for a cannulas.

Background of the Invention Presently, cannulas are used in the medical profession to provide an opening into a body cavity, generally a vein, through which a needle of a syringe or intravenous drip can be inserted and subsequently removed. Use of a cannula advantageously allows repeated insertion and removal of needles whilst creating only a single hole in the body.

A cannula consists of an elongate, narrow tube that opens out at one end to provide a section of a significantly greater diameter. A flange is attached to the tube, generally in the region of the wider section. To insert the cannula into a body a needle is inserted into the tube from the wider end of the tube towards the narrower end the tube and the needle and tube are then inserted into the body. The needle can subsequently be removed leaving the narrower section of the tube inside the body. The flange is generally used to provide a means of fastening the cannula against the outer surface of the body using an adhesive tape, for example.

Unfortunately, when the interior end of the cannula is inserted into a fluid reservoir within a body and the needle is removed, either during insertion of the cannula

or afterwards during use thereof, fluid often leaks out of the exterior end of the cannula. When the cannula is inserted into a vein, this fluid is blood, which can provide a health risk. The amount of fluid that leaks out of the cannula can vary, but is often a significant amount.

Whilst cannulas are generally provided with stoppers to prevent continued leakage of fluid out of the cannula, there is often an unacceptable amount of fluid leakage before the stopper can be inserted.

It is an aim of preferred embodiments of the present invention to reduce the problems of the prior art, either as stated herein or otherwise.

Summary of the Invention According to a first aspect of the invention, there is provided a valve comprising a folded sheet material.

Suitably, the sheet material is folded in such a manner that fluid flow in one or more directions is restricted. Preferably, fluid flow in only one direction is restricted.

Suitably, the valve is a unidirectional valve. Suitably, the valve is a flow control valve. Suitably, the valve controls fluid flow in one or more directions.

Suitably, the valve is suitable for a cannula or other medical equipment. The valve may be for a peripheral or

central intravenous cannula or a sub-clavian cannula, for example.

Suitably, the sheet material comprises a plastics material. Suitable plastics materials include polyethylene types of plastics.

The sheet material is suitably of a minimal thickness suitable to obtain the desired structural rigidity of the valve.

Suitably, the valve comprises a single length of sheet material. However, the sheet material may comprise a plurality of sections joined together.

The sheet material suitably comprises a resilient material. Suitably, the sheet material is sufficiently

resilient for the valve to automatically revert to a t, closed condition upon removal of an opening force.

The valve may revert from an open to a closed condition on removal of an opening force, by the action of a backpressure in the restricted direction.

Closure of the valve may be effected by a combination of the resilience of the valve material and the back-pressure in the valve.

Suitably, the sheet material is an elongate section of material. The elongate section may be substantially rectangular in shape when in an unfolded condition. Suitably, the rectangular elongate section has a first

longer edge that is substantially a straight edge. Suitably, the first longer edge is straight along substantially the full length thereof. The second longer edge of the rectangular elongate section may comprise a straight edge or a non-straight edge.

Suitably, the elongate section of sheet material comprises a first set of fold lines. Suitably, the first set of fold lines provides a continuous zig-zag fold line along the length of the sheet material. Suitably, each trough and crest of the zig-zag fold line is provided by the abutment of an end of each of two adjacent fold lines.

Suitably, the abutment of adjacent fold lines provides the troughs and crests of the zig-zag fold line as sharp corners.

Suitably, each trough of the zig-zag fold line intersects the first longer edge of the elongate section of sheet material and each crest of the zig-zag fold line intersects the second longer edge thereof.

Suitably, the first set of fold lines defines a plurality of substantially triangular sections in the sheet material when folded. Suitably, the substantially triangular sections are adjacent one another. Suitably, corners of adjacent triangular sections abut one another.

Suitably, the first set of fold lines and the second longer edge define a series of polygonal sections.

If the second longer edge of the elongate section of sheet material is a straight edge, then the polygonal sections

will provide a second series of substantially triangular sections in the sheet material when folded.

In this case, the troughs of the zig-zag fold line will define the length of the base of the first series of triangular sections and the apex of the second series of triangular sections. Furthermore, the crests of the zigzag fold line will define the apex of the first series of triangular sections and the length of the base of the second series of triangular sections.

Suitably, the plurality of triangular sections in either the first or second series are orientated in substantially the same direction.

Generally, unless stated otherwise herein or otherwise required by the context, a triangular section may be an equilateral, isosceles, scalene, acute, obtuse or right angle triangle.

Each series of triangular sections may comprise one type of triangular shape or a combination thereof.

If the second longer edge of the elongate section of sheet material is not a straight line, then the polygonal sections may not be substantially triangular sections.

For example, if the second longer edge has a zig-zag shape, the polygonal sections may be trapezoidal or rhomboidal sections.

Suitably, the base of each of the plurality of triangles of the first series of triangular sections is provided by a section of the first longer edge of the elongate section

of sheet material. If the triangles are isosceles triangles, preferably the short edge is provided by the first longer edge of the elongate section.

Suitably, the second longer edge provides one or more edges of the polygonal sections.

If the polygonal sections are triangular, the base of each of the plurality of triangles of the second series of triangular sections is suitably provided by a section of the second longer edge of the elongate section of sheet material. If the triangles are isosceles triangles, preferably the short edge is provided by the second longer edge of the elongate section.

Suitably, all, or substantially all, of the plurality of triangles of one or both series thereof are substantially the same shape. Suitably, all, or substantially all, of the plurality of triangles of one or both series thereof have substantially the same dimensions.

The first and/or second series of triangular sections may comprise a series of triangles having the same dimensions excepting the triangle at each end of a series. In this case, the series of triangles are suitably either equilateral or isosceles triangles and each end triangle is a right angle triangle.

The end triangles may be half the size of the other triangles in the series. Suitably, the end triangles have dimensions equivalent to another triangle of the series cut in half along a line extending from the apex of the

triangle and bisecting the base of the triangle at 900 to the base line.

Suitably, all, or substantially all, of the polygonal sections are substantially the same shape and size.

The sheet material may further comprise a second set of fold lines. Suitably, the second set of fold lines comprises a plurality of discrete fold lines. Suitably, the plurality of discrete fold lines are substantially parallel to one another, when the sheet material is in an unfolded condition.

Suitably, one or more, and preferably each, fold line of the second set extends from the first longer edge of the sheet material to the second longer edge of the sheet material.

Suitably, each fold line of the second set of fold lines extends from the first longer edge at a point of intersection of a trough of the zig-zag first fold line with the first longer edge.

Suitably, each second fold line extends from the first longer edge of the sheet material at 900 to that edge.

Suitably, each point of intersection of a trough of the first zig-zag fold line with the first longer edge of the elongate sheet material has a fold line of the second series of fold lines extending from it.

Suitably, the folds of the second set of fold lines are reverse scored fold lines compared to the first set of fold lines.

If the second longer edge has a zig-zag shape, one or more, and preferably each, trough of the zig-zag second longer edge suitably intersects with a crest of the first zig-zag fold line; or in other words, the apex of a triangular section from the first series of triangular sections.

Suitably, one or more, and preferably each, crest of the zig-zag second longer edge intersects a second fold line extending from, and at 900 to, the first longer edge to the second longer edge of the elongate section of sheet material.

Suitably, at a point of intersection of a first fold line and the second longer edge of the sheet material the interior angle, angle A, between the second longer edge and an adjacent first fold line is about 900 or less.

Suitably, angle A is greater than 30 , preferably greater than 450 and most preferably greater than 600.

Preferably, angle A is substantially 900.

In order to construct a valve from the sheet of material, the sheet is folded along the first fold lines, in a first direction, and along the second fold lines in an opposite direction to the direction in which the first fold lines are folded.

As the sheet is folded, the ends of the folded sheet material come together into an abutting relationship.

Suitably, the ends are brought together in such a way that the apexes of the first set of triangular sections all abut one another in a central region of the valve.

One or both ends of the sheet material may comprise a tab, which tab (s) can be used to attach one end to the other.

Suitably, the side walls of the first set of triangular sections abut one another when the two ends of the sheet material are abutting.

Suitably, the polygonal sections are folded substantially in half by means of the second set of fold lines. In this case, when the two ends of the sheet material are abutting, the folded polygonal sections provide spines extending from the surface provided by the abutting first triangular sections. These spines advantageously, strengthen the valve.

In a closed condition, the apexes of the first triangular sections meet at a central region of the valve. The side walls of the triangular sections about one another to provide an exterior surface and an interior surface. The spines formed by folding the second fold lines suitably extend from the interior surface.

Providing the sheet material with a substantially straight first longer edge will result in a valve having a polygonal circumferential shape when folded. In order to provide a valve with a circumferential shape which is closer to a circular circumference, the shape of the first

zig-zag fold line may be modified to provide a greater number of narrower first triangular sections. Alternatively, or in addition, the first longer edge may be modified so that it provides a scalloped edge rather than providing a straight edge.

In use of a valve in accordance with the present invention, a force is applied to the meeting point of the apexes of the first triangular sections on the exterior surface of the valve. Application of a force at this point will move the valve from a closed condition to an open condition. Maintenance of force will maintain the valve in the open condition. Upon removal of the force, the valve will automatically revert to the closed condition, thus restricting fluid flow through the valve from the interior side thereof. Closing of the valve may be assisted by the pressure of fluid flow in the restricted direction.

According to a second aspect of the invention there is provided a tube in which tube is located a valve according to the first aspect of the invention.

Suitably, the tube is part of a cannula.

Suitably, the length of the elongate section of sheet material of the valve is substantially equal to the inner circumference of tube in which the valve is located.

The spacing of the troughs of the zig-zag first fold line are suitably such that the sum of the angles of the apexes

of the first set of triangular sections is substantially 3600.

The distance from the base to the apex of the first set of triangular sections of the folded sheet is suitably, substantially equal to the radius of the tube in which the valve is located.

Suitably, the first longer edge of the valve is located about the inner circumference of the tube.

The valve may further comprise a marginal flange extending from a portion at least of the first longer edge of the valve. The marginal flange may be used to attach the valve to the inner wall of the tube.

Suitably, the valve is located in the tube with the spines provided by the folding of the second set of fold lines being located upstream of the direction in which fluid flow is desired to be restricted.

If the tube is a cannula, the valve is suitably located in the wider section of the cannula and the spines produced by folding the sheet along the second set of fold lines suitably extend towards the narrow section of the tube.

According to a third aspect of the invention there is provided a kit comprising a valve in accordance with the first aspect of the invention and a tube, in which the valve can be located.

Suitably, the tube is a cannula.

A valve in accordance with the present invention advantageously allows insertion and removal of an article, such as a needle, through the valve, but upon removal of the article from the valve the valve closes to prevent fluid flow in the restricted direction. In particular, a cannula comprising a valve in accordance with the present invention can be used without significant blood leakage therefrom.

The valve does not hinder the flow of fluids in the unrestricted direction, for example from a syringe or intravenous drip into a body in which the cannula is located. Furthermore, the valve will not impede removal of fluid samples through a cannula.

In addition, the valve will not restrict the liquid flashback feature of conventional cannulas, that allows the user to determine when the cannula is correctly positioned in the body.

Brief Description of the Figures The present invention will now be described, by way of example only, with reference to the following drawings, in which: Figure 1 is a schematic plan view of a valve in an unfolded condition; Figure 2 is a schematic perspective plan view of the valve of figure 1 in a partially folded condition ;

Figure 3 is a plan view from one side of the valve of figures 1 and 2 in a folded condition ; Figure 4 is a cross-sectional view along line X-X of figure 3; Figure 5 is a schematic plan view of a cannula; Figure 6 is a schematic longitudinal cross-sectional view through the cannula of figure 5, showing the valve in a closed condition, and Figure 7 shows the cannula of figure 6 with the valve in an open condition.

Description of a Preferred Embodiment of the Invention The valve of figure 1 comprises an elongate section 2 of a

sheet material. The elongate section 2 has a generally j \ rectangular shape and comprises a first longer edge 4, a second longer edge 6, and two ends 8, 10.

The first longer edge 4 is a straight edge, whereas the second longer edge 6 has a substantially zig-zag shape. The zig-zag second longer edge 6 comprises crests 12 and troughs 14.

The elongate section 2 of sheet material further comprises a first set of fold lines 16, denoted by dashed lines in the figures. The first set of fold lines 16 form a zigzag fold line 18 extending from one end 8 to the other end 10 of the elongate section 2. The zig-zag fold line 18 comprises crests 20 and troughs 22 formed by intersections

of the ends of the individual fold lines of the first set of fold lines 16. The crests 20 of the zig-zag fold line 18 intersect with the troughs 14 of the zig-zag second longer edge 6 of the elongate section 2 of sheet material.

The troughs 22 of the zig-zag fold line 18 are substantially directly opposite the crests 12 of the zigzag second longer edge 6 of the elongate section 2 of sheet material.

The troughs 22 of the zig-zag fold line 18 intersect the first longer edge 4 of the elongate section 2 of sheet material.

As can be clearly seen from figure 1, the troughs 22 of the zig-zag fold line 18 define the base 24 of a first set of triangular sections 26. The first set of triangular sections 26 are defined by the zig-zag fold line 18 and the first longer edge 4 of the elongate section 2.

The first set of triangular section 26 comprises a series of substantially equilateral triangles 28, excepting the end two triangular sections 30, which comprise right angle triangular sections.

The equilateral triangular sections 28 comprise side walls 36 and a base 24. The right angle triangular sections 30 have aide walls 36,38.

The right angle triangular sections 30, are substantially half the size of the equilateral triangles. Therefore,

when the two ends 8, 10 of the elongate section 2 meet, the side walls 38 of the right angle triangular sections 30 abut, and a triangular section of dimensions substantially equal to the equilateral triangular sections 28 of the series is formed.

The zig-zag fold line 18 and the second longer edge 6 define a set of polygonal sections 32.

The interior angle between the zig-zag second longer edge 6 and the adjacent side wall 36 of each triangular section 26 is shown as angle A. In the embodiment illustrated angle A is 900. The advantage of using an angle of 900 for angle A is that the edges 48 of the zig-zag second longer edge 6 abut one another when the sheet 2 is in the folded condition (as shown in figure 4).

If the second longer edge 6 of the elongate section 2 of

sheet material was a straight edge (not shown), then the t polygonal sections 32 would provide a second set of triangular sections (not shown).

The elongate section 2 of sheet material further comprises a second set of fold lines 34, denoted by broken lines in the figures.

The second set of fold lines 34 comprises a series of discrete fold lines. The discrete fold lines 34 extend from the first longer edge 4 to the second longer edge 6.

As can be clearly seen from the figures, each of the second set of fold lines 34 extend from a trough 22 of the zig-zag fold line 18 to a crest 12 of the zig-zag second longer edge 6.

As can be clearly seen from figure 1, each second fold line 34 bisects the polygonal sections 32 along a central line to form to sections 40,42.

The second fold lines 34 are reverse scored relative to the first zig-zag fold line 18.

To make use of the valve of figure 1, the sheet material 2 is folded in one direction along the first zig-zag fold line 18 and folded in an opposite direction along each of the second fold lines 34.

Folding the sheet material 2 has the effect of defining the triangular sections 26. As the sheet material 2 is folded the ends 8,10 thereof come towards one another as do the side walls 36 of the triangular sections 26. Also, as the sheet 2 is folded the sections 40,42 of each polygonal section 32 move into a face to face relationship.

In a fully folded condition, as shown in figures 3 and 4, adjacent side walls 36 of the triangular sections 26 abut as do the side walls 38 of the end triangular sections 30. The apex'44 of each triangular section 26 meets in a central region. Furthermore, the sections 40,42 of the polygonal sections 32 overlie one another in a face to face relationship and form spines 46. The spines 46 extend substantially perpendicular to the plan of the triangular sections 26.

As can be seen from figure 3, providing the sheet material 2 with a straight first longer edge 4 results in a valve

having a polygonal (in this case hexagonal) circumferential shape when folded. In order to provide a valve with a circumferential shape which is closer to a circular circumference, the shape of the zig-zag fold line 18 may be modified to provide a greater number of narrower triangular sections 26.

Alternatively, or in addition, the first longer edge 4 may be modified so that it provides a scalloped edge rather than providing a straight edge (not shown).

Figures 5-7 illustrate a valve as shown in figures 1-4, and as described above, in located in a cannula.

Figure 5 shows a cannula 50, comprising a tube 52 having a narrower section 54 and a wider section 56.'The cannular 50 further comprises a flange 58. A valve 60 is located in the end of the wider section 56 of the cannula 60 at the end distal the narrower section 54.

As can be seen more clearly from Figure 6, the valve 60 is positioned in the cannula 50 in the folded condition (as illustrated in figure 3), with the first longer edge 6 contacting the inner wall of the tube 52.

The valve 60 is orientated such that the triangular sections 26 face the distal end 62 of the tube 52 and form an exterior surface of the valve and the spines 42 provided by the polygonal sections 32 of the valve 60 extend towards the narrower section 54 of the tube 52, and form an interior surface of the valve 60.

Figure 6 illustrates the valve 60 in a closed condition.

In this condition, liquid flow in the direction indicated by arrow R is restricted. The spines 46 advantageously strengthen the valve 60 and reduce the likelihood of the fluid pressure in the direction R forcing the spines 46 through towards the distal end 62 of the tubes 52.

The valve 60 can be opened by applying a force to the central region of the exterior surface of the valve 60, in a direction illustrated by arrow P.

Figure 6 shows a needle 64 which has been inserted into The cannula 50 through the valve 60. In opening the valve 60, the triangular sections 26 are pushed inwards and the spines 46 are pushed out towards the inner wall of the cannula 50.

When the needle 64 is withdrawn from the cannula 50, the Triangular sections automatically move outwards and the spines 46 move inwards until the valve 60 is in the closed condition as shown in Figure 6 as a result of the resilient nature of the sheet material 2 and any fluid pressure in the restricted direction R.

To prevent stagnation of blood whilst the valve is in the fully open position within the acute angle of the cannula lumen, 65, a projection is formed within the cannula body 56. This structure matches the profile of the fully inserted syringe. Figure 8 and 9.

This projection 66 encourages the blood away from the angle by the insertion of the syringe/fluid administration set 67. Figure 10.

The length of this projection is dependent upon the diameter of the valve 60. Furthermore this projection may be included in the bonding process of the valve to the cannula lumen.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment (s). The invention extends to any novel one or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one or any novel combination, of tkq steps of any method or process so disclosed.

Claims (9)

1. CLAIMS 1. The valve is comprised of a single sheet of polyethylene type plastic
2. 2. The valve consists of several triangular sections created by folds in the above mentioned material to provide rigidity to the structure
3. 3. The valve is unidirectional allowing the control of fluids in one or more directions
4. 4. The valve is suitable for an cannula or other medical equipment
5. 5. The resilience of the valve material enables the valve to automatically revert to a closed condition upon removal of the opening force
6. 6. Full closure of the valve is effected by a combination of the resilience of the valve material and the back pressure of the valve
7. 7. The inner profile of the cannula lumen prevents the entrapment and subsequent stagnation of fluid when the valve is in the open position
8. 8. The inner profile allows the insertion/bonding of the valve to the cannula body
9. 9. The valve is substantially described herein with reference to Figures 1-10 of the accompanying drawing