Abstract:
A cannula valve arrangement made from a suitably resilient polymeric material including a body ( 10 ) having a substantially cylindrical cavity ( 16 ) for receiving a medical apparatus hub ( 32, 34 ) and a sleeve ( 14 ) having a bore ( 18 ) for receiving a cannula ( 28 ), which is open into the body cavity. A zone ( 20 ) of the body wall which defines the cavity ( 16 ) is convexly bulged from the body ( 10 ) and is adapted to snap from its convex shape into a concave shape in the body cavity ( 16 ) when pressed over-center into the body to close the bore ( 18 ) of the sleeve ( 14 ) to the cavity until again moved outwardly from the cavity ( 16 ).

Description:
FIELD OF THE INVENTION 
     This invention relates to a shut-off valve arrangement for occluding the flow of a fluid through the bore of a cannula. 
     In this specification the term cannula is intended to include a catheter or any other conduit for introducing liquid into or draining fluid from the body of a patient. 
     BACKGROUND TO THE INVENTION 
     Various valve arrangements for occluding the flow of a body fluid through a fluid flow or infusion instrument are well known. Most of the known valve arrangements generally fall into two classes: those which include few components and are so inexpensive and those which include several separately manufactured components which require to be assembled and which are consequently more expensive. Typical examples of the valve arrangements of the first type are those disclosed in U.S. Pat. Nos. 4,198,973 and 5,429,616 which pinch the fluid bore in a catheter or cannula closed by some finger operated mechanism and which again opens the passage when the finger pressure on the mechanism is released. Although these valve arrangements are relatively cheap compared to the valve arrangements of the second type they require hands-on operation while closing the fluid passage of the conduit to which they are connected so restricting free hand use of the person who is inserting or removing the catheter or cannula into or from the body of a patient. 
     OBJECT OF THE INVENTION 
     It is the object of this invention to provide a simple single piece cannula valve arrangement which is simply closed for hands-off insertion into or removal from the body of a patient. 
     SUMMARY OF THE INVENTION 
     A cannula valve arrangement which is made from a suitably resilient polymedic material including a body having a substantially cylindrical cavity for receiving a medical apparatus hub and a sleeve having a bore, for receiving a cannula, which is open into the body cavity according to the invention is characterised in that a zone of the body wall which defines the cavity is convexly bulged from the body and has a wall thickness which is less than that of the remainder of the body to enable the bulged portion of the body to snap from its convex shape into a concave shape in the body cavity when pressed over-centre into the body to close the bore of the sleeve to the cavity until again pressed outwardly from the cavity. 
     The diameter of the catheter sleeve bore may be significantly less than the diameter of the portion of the body which defines the cylindrical cavity with the axis of the sleeve bore being parallel to and eccentrically displaced from the axis of the cylindrical cavity with a transition portion of the body between the cylindrical cavity portion and the sleeve defining the bulged zone of the body. 
     The mouth of the cannula sleeve bore in the cylindrical cavity conveniently defines a valve seat and the inner surface of the bulge zone of the body carries an inwardly projecting valve member which when the bulged portion of the body is pressed into the cylindrical cavity closes the sleeve bore. The junction between the bulged portion of the body and the sleeve is preferably made in the form of a plastic hinge which is linear and normal to the direction of the cylindrical cavity and the sleeve bore axes. 
     The valve arrangement preferably includes a cannula which is fixed to the body sleeve with its bore in alignment with the sleeve bore. 
     The valve arrangement may include a needle which is eccentrically located in a hub with the needle projecting from the cannula and the hub located in the cylindrical cavity of the body with its leading end clear of the valve member in the cavity. 
     The invention additionally extends to a needle for use with the valve arrangement of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An embodiment of the invention is now described by way of example only with reference to the drawings in which: 
     FIG. 1 is a perspective view of the valve arrangement body of the invention as seen from the front, above and one side, 
     FIG. 2 is a similar view to that of FIG. 1 illustrating the valve arrangement body from the rear, 
     FIG. 3 is a sectioned side elevation of the valve arrangement body, 
     FIG. 4 is an end elevation of the FIG. 3 body, 
     FIG. 5 is a plan view of the FIG. 1 body shown sectioned on the line  5 — 5  in FIG. 3, 
     FIG. 6 is a under plan view of the FIG. 3 body shown sectioned on the line  6 — 6  in FIG. 3, 
     FIG. 7 is a sectioned side elevation of the valve arrangement body shown in the closed position of the valve and including a cannula, 
     FIG. 8 is a sectioned side elevation of a needle and hub for use with the valve arrangement of the invention, and 
     FIG. 9 is a sectioned side elevation of the valve arrangement of the invention ready for use. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The valve arrangement of the invention is shown in the drawings to include a body  10  which is composed of a cylindrical body portion  12  and a cannula sleeve  14 . The cylindrical portion  12  of the body is open at the forward end of the body and closed at its rear end to define a cylindrical cavity  16  with the bore  18  of the sleeve portion  14  of the sleeve being in communication with the cavity  16  as is shown in FIG.  3 . 
     The valve arrangement body  10  is moulded economically in one piece, using a single core mould, from a resilient medical grade plastic material such as polypropylene, nylon or the like. It may, however, be made from a suitable rubber or like material which has the required stiffness and resilience for its operation as will be explained below. 
     As is best appreciated from FIG. 3 the cylindrical portion  12  of the body has a significantly greater diameter, which is engageable with conventional LUER slip medical hub spigots, than the vertical cross-sectional dimension of the sleeve  14 . The upper rear surface portion of the body portion  12  is convexly curved downwardly onto the flattened upper surface of the sleeve  14 . The portion of the wall of the cylindrical portion  12  of the body, above the upwardly inclined dotted line in FIG. 3, is thinned down to a smaller dimension than that of the remainder of the wall of the body portion  12  to provide what amounts to a resiliently flexible bulge zone  20  which includes, to the rear of its inner surface, an inwardly projecting valve member  22 . The straight line junction position between the bulge zone  20  and the flat upper surface of the sleeve  14  is formed to provide a linear plastic hinge  24  which is normal to the axes of the cylindrical cavity  16  and the sleeve  14 . The wall thickness of the bulge zone around the valve member  22  is slightly thickened relatively to the wall thickness of the upper forward part of the bulge zone. 
     The opening into the bore  18  of the sleeve  14  in the body cavity  16  is surrounded by a downwardly sloping slightly concave land  26  which, with the opening to the bore, defines a seat for the valve member  22 . 
     A flexible cannula  28 , shown in FIG. 7, is fixed in the sleeve  14  by means of a suitable adhesive with its bore in axial register with the sleeve bore. 
     A needle for use with the valve arrangement of the invention is illustrated in FIG.  8  and is shown in the drawing to include a conventional metal needle  30  which is eccentrically located in a conventional needle hub  32  to cater for the offset eccentricity of the axes of the cylindrical cavity  16  and the bore  18  of the sleeve  14  of the valve arrangement of the invention. As is seen in FIG. 9, the length of the body cavity  16  is such that the leading end of the needle hub  32  is clear of the valve member  22  when the hub is inserted fully into the cavity. 
     In use, for example in an intravenous drip procedure, a conventional air pervious blanking hub  34  is inserted into the needle hub  32  cavity as shown in FIG.  9 . The needle  30  and cannula  28  are then located in the patient&#39;s vein. The transparent hub  34 , as is conventional, serves as an indicator that the needle  30  is correctly located when it becomes blood filled. The person carrying out the procedure then presses down with a finger on the rear portion of the bulge zone  20  and withdraws the needle  30 , together with the plug  34 , from the patient. As the sharpened tip of the needle passes the valve member  22 , which is pressed down on the needle  30  as it is withdrawn from the body  10 , the bulge zone is pressed downwardly into the cavity  16  of the body  10  The bulge zone  20  obviously has a greater area than its more rigid surround, the dotted line in FIG. 3, and this larger area together with the fairly stiff resilience of the plastic material from which it is made causes the material of the bulge zone to snap into the body with an over-centre action as it is pressed inwardly beyond the dotted line position in FIG.  3 . When the bulge zone  20  has snapped into the cavity  16  of the body the valve member  22  is closed firmly onto its seat  26  to obturate the sleeve bore  18  and that of the cannula  28  connected to it, as shown in FIG. 7, to prevent blood flow from the patient. The bulge zone  20  is held in its FIG. 7 closed position by the bowed spring effect of the material from which the body  10  is made. 
     An important feature of the invention is that the linear hinge  24  holds the valve member  22  against skewing while being moved from its open to its closed position of operation, even under a misdirected closing pressure, to ensure accurate and positive engagement of the valve member  22  with its seat. 
     An outlet hub from a conventional giving set is now pressed into the cavity  16  of the body  10  of the valve arrangement. On entering the cavity  16  the nose of the giving set hub will press against the forward end of the now concave bulge zone  20  with further pressure on the hub causing the bulge zone to be rolled upwardly until, under the resilience of its material, it is caused to snap out of the cavity  16  back to its FIG. 3 position and in so doing to open the fluid passage through the body  10  and the giving set conduit to the patient. 
     From the above description of the valve arrangement of the invention it will be appreciated that the one-piece body  10  is simple and inexpensive to manufacture and because of the positive and locked closing action of its valve member it enables the hands of the person carrying out the insertion procedure to be totally freed to perform tasks, other than pressing veins closed and so on, while connecting a giving set to the valve assembly of the invention. 
     The invention is not limited to the precise details as herein described. For example, the cylindrical portion  12  of the body  10  could be made longer than shown in the drawings and be made to include an infusion port. Additionally, to open the closed valve without having to press an object into the body cavity  16  the bulge zone  20  could be made to include a small trigger formation which in the FIG. 3 position of the bulge zone will project rearwardly from behind the valve member to be approximately parallel to the sleeve  14  and which in the FIG. 7 position of the bulge zone will point upwardly from where it may be pressed downwardly towards the sleeve  14  to snap the bulge zone out of the body cavity  16 . Yet further, if the valve arrangement of the invention is to be used as a urinary catheter it would be moulded from a suitable rubber or rubber-like material with the sleeve  14  being considerably extended and suitably shaped in cross-section beyond the hinge  24  to provide the catheter.