Abstract:
A catheter for insertion into a body cavity of a subject (such as the urinary bladder), and having a drainage tube extending from a drainage opening adjacent a distal end of the catheter to a drainage outlet adjacent a proximal end of the catheter; a closure member mountable for sliding movement within the drainage tube between a first position such that said drainage opening is in fluid communication with the drainage outlet and a second position wherein the closure member blocks fluid communication between the drainage opening and the outlet port; and an actuator, operable from the proximal end of the catheter, to move the closure member between the first and second positions. The closure member can include a second tube, sliding within the drainage tube, or a slideable plug.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to catheters for draining fluids from body cavities of human or animal subjects and especially for those catheters that can also instill a medicament into the cavity following drainage. The invention is especially concerned with such catheters for draining urine from the urinary bladder of a subject and instilling a medicament therein. 
       BACKGROUND AND PRIOR ART KNOWN TO THE APPLICANT 
       [0002]    There are a number of conditions that require patients to manually drain urine from the bladder at intervals, and this can be performed either under the supervision of an attending physician or healthcare worker, or on occasions can be performed by a patient themselves. One such common condition is an overactive bladder. For many conditions it is also necessary to deliver a medicament to the bladder. For this to be successful, it is important that the bladder is initially drained of any accumulated urine to prevent dilution of the medicament, so allowing a pre-determined dose to be applied. Direct application of medicaments to the interior of the bladder, known as “intravesical” administration is becoming more common, and one such specialised catheter to allow drainage and intravesical administration is described in UK patent GB 2448892. In this device, a urinary cannula is described, and that comprises a number of channels extending from a proximal to a distal end of the catheter. There is a drainage channel to allow urine to flow from one end to the other; and installation channel to allow medicament to be delivered from the proximal to the distal end and a control channel to allow a viscous control fluid to be delivered to a cuff located within the drainage channel. In some embodiments a further channel is provided to allow delivery of a fluid to a balloon adjacent to the external wall of the catheter, known as a Foley balloon, which may be inflated to secure the end of the catheter at the correct position in the bladder after insertion via the urethra. 
         [0003]    Such devices are complex and expensive to manufacture, and it is an object of the present invention to provide an improved such catheter. 
       SUMMARY OF THE INVENTION 
       [0004]    Accordingly, the invention provides a catheter for insertion into a body cavity of a subject, comprising: a drainage tube extending from a drainage opening adjacent a distal end of the catheter to a drainage outlet adjacent a proximal end of the catheter; a closure member mountable for sliding movement within said drainage tube between a first position such that said drainage opening is in fluid communication with said drainage outlet and a second position wherein said closure member blocks fluid communication between said drainage opening and said outlet port; and an actuator, operable from the proximal end of the catheter, to move said closure member between said first and second positions. In this way, a simplified device is provided, having a slideable closure member, rather than an internally-mounted inflatable balloon as previously provided on such catheters. This simplifies manufacture, and also simplifies operation, as the valve closure mechanism is less likely to be confused with the other ports often seen on such catheters. This is especially important if the device is to used by the patient themselves. 
         [0005]    Preferably, the catheter further comprises an instillation lumen extending from an instillation port adjacent a proximal end of the catheter to an instillation outlet adjacent a distal end of the catheter. More preferably, the catheter further comprises a non-return valve configured to resist flow in said instillation lumen in a direction from the distal end to the proximal end. 
         [0006]    In preferable embodiments, said actuator is configured to move said closure member between said first and second positions irreversibly. In this way, re-use of the device is prevented, thereby reducing the risk of cross-infection. 
         [0007]    In a first preferable variant, said closure member comprises a plug and said actuator comprises a filament attached to said plug, said filament extending to the proximal end of the catheter. 
         [0008]    In a second preferable variant, said closure member comprises a secondary tube located within said drainage tube, said secondary tube having an aperture in its wall such that, in said first position said aperture fluidly communicates with said drainage opening and in said second position said fluid communication is blocked, and wherein said secondary tube extends to the proximal end of said catheter such that it may be manipulated to slideably move said tube between its first and second positions, thereby acting as said actuator. 
         [0009]    Preferably, the second variant is configured such that said sliding movement is in an axial direction. More preferably, the cross-sectional profile of said drainage tube and the profile of the outside surface of said secondary tube are so shaped as to resist relative rotational movement therebetween whilst allowing relative axial movement therebetween. 
         [0010]    In an alternative arrangement, the second variant is configured such that said sliding movement comprises rotation of said secondary tube relative to said drainage tube. Preferably, a cooperating indent and detent are provided on the outside surface of said secondary tube and the internal wall of said drainage tube configured to allow relative rotational movement between the secondary tube and the drainage tube whilst resisting relative axial movement therebetween. 
         [0011]    In any aspect or variant of the invention it is preferred that a lubricating agent is provided between said closure member and the internal wall of said drainage tube to facilitate relative movement therebetween and/or to provide a fluid resistant seal therebetween. 
         [0012]    In any aspect of the second variant, it is preferred that a ratchet mechanism is provided to ensure irreversible movement of the secondary tube relative to the drainage tube. 
         [0013]    In any aspect of either variant, it is also preferred that the catheter further comprises a balloon adjacent an external wall of the catheter near its distal end and proximal of said drainage opening and connected through a balloon control channel to a balloon control port at the proximal end, the balloon being inflatable and deflatable to respectively increase and decrease the local diameter of the catheter to allow reversible anchoring of the catheter within a body cavity. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIGS. 1 and 2  illustrate an axial cross-section of the distal end of a catheter of the present invention; 
           [0015]      FIG. 3  illustrates a transverse cross-section of a catheter of the invention; 
           [0016]      FIGS. 4 and 5  illustrate transverse cross-sections of the distal end of a catheter of the invention; 
           [0017]      FIGS. 6-8  illustrate transverse cross-sections of embodiments of a catheter of the invention; 
           [0018]      FIGS. 9 and 10  illustrate axial cross-sections of a distal and proximal end respectively of an embodiment of the invention; 
           [0019]      FIGS. 11-13  illustrate axial cross-sections of a distal end of a catheter of the present invention; and 
           [0020]      FIGS. 14-16  illustrate a delivery means for a medicament suitable for use with a catheter in accordance with the invention. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0021]      FIG. 1  illustrates, in axial cross-sectional view, the distal end of a catheter of the present invention, generally indicated by  1 . In this embodiment, there is provided a drainage tube  2  that extends from a drainage opening  3  adjacent the distal end  4  of the catheter to a drainage outlet adjacent a proximal end of the catheter (not illustrated). The drainage tube  2  is constructed of a flexible material, such as a silicone-based plastics material or latex. The diameter of the catheter is so sized as to be able to be introduced into a body cavity of a subject for example through a urethra. In the embodiment of  FIG. 1  the drainage tube  2  is sealed at its distal end by a cap  5  securely fitted to the end of the tube  2 . 
         [0022]    A closure member in the form of a secondary tube  7  located within the drainage tube  2 . The bore of the drainage tube  2  and the outside diameter of the secondary tube  7  are so sized as to provide a relatively snug fit, whilst allowing the secondary tube  7  to slide within the drainage tube  2  along its full length. In this embodiment, the secondary tube  7  is provided with an aperture  8  in its wall that, in a first position as illustrated in  FIG. 1 , fluidly communicates with the drainage opening  3  in the drainage tube and thus with the lumen of the secondary tube  7 . 
         [0023]    The secondary tube  7  may be slid within the drainage tube to a second position, illustrated in  FIG. 2 , such that the aperture  8  is no longer in fluid communication with the drainage opening  3  thereby blocking flow of a fluid through the drainage opening  3  and down the drainage tube or secondary tube. In the embodiment shown in  FIGS. 1 and 2 , the end of the secondary tube  7  is also sealed, for example with a cap or a plug  9 . In this way, if the end of the secondary tube  7  is withdrawn to a distance past the drainage opening  3  towards the proximal end of the catheter, fluid can still not flow through the drainage tube and down the secondary tube. 
         [0024]    Also included in this embodiment is an installation lumen  10 , located within the wall of the drainage tube  2 , that extends from an installation outlet  11  adjacent the distal end  4  of the catheter to an installation port adjacent the proximal end of the catheter (not illustrated). 
         [0025]      FIG. 3  shows a particularly preferred configuration of this embodiment, as a transverse cross-section along the line A-A of  FIG. 1 . In this embodiment, the bore of the drainage tube  2  is provided with a shaped profile, in the form of a flat section  12  running the length of the drainage tube, and the outside surface of the secondary tube  7  is provided with a similarly shaped flat surface portion  13  that co-operates with the flat  12  to resist rotational movement of the secondary tube with respect to the drainage tube. In this way, the configuration ensures that the aperture  8  in the secondary tube can be correctly aligned with the drainage opening  3 . 
         [0026]    It will be appreciated that in embodiments of the catheter, multiple drainage openings  3  may be provided around the periphery of the drainage tube, for example two such outlets, to ensure that flow can be maintained even if one outlet becomes blocked. It will be understood that in this situation, corresponding multiple apertures  8  in the secondary tube will also be provided. 
         [0027]      FIGS. 4 and 5  illustrate alternative configurations of the distal end of a catheter  1  of the present invention again in axial cross-section. Features in these embodiments that correspond with those of  FIGS. 1 and 2  are numbered accordingly. The key difference between this embodiment and the embodiment of  FIGS. 1 and 2  is that the secondary tube  7  is not provided with an end cap  9 . It can be seen that if the drainage tube  2  and secondary tube  7  are arranged in such a way that the secondary tube  7  can only be moved from its first position (illustrated in  FIG. 4 ) to a second position (illustrated in  FIG. 5 ) by moving the secondary tube  7  towards the distal end  4  of the catheter, then such a cap on the secondary tube becomes unnecessary, as the wall of the secondary tube will always provide an adequate seal for the drainage opening  3 . 
         [0028]      FIG. 6  illustrates an alternative configuration of a cross-section of a catheter of the present invention taken at a position equivalent to A-A of  FIG. 1  and in which two drainage openings  3  are provided, together with two apertures  8  in the wall of a secondary tube  7 . Again, an installation lumen  10  is provided, moulded into the wall of the drainage tube  2 . In this embodiment, the installation lumen defines a protuberance  13  in the inner wall of the drainage tube  2  that matches a longitudinal groove  14  along the outside wall of the secondary tube  7 . These correspondingly-shaped profiles again provide a resistance against relative rotational movement between the drainage tube and the secondary tube, ensuring axial alignment of the apertures  8  with the drainage openings  3 . 
         [0029]      FIG. 7  illustrates an alternative cross-section, again at a position corresponding to section A-A of  FIG. 1  in which the sliding movement of the secondary tube  7  relative to the drainage tube  2  is a relative rotational movement such that the drainage opening  3  may be aligned or, as illustrated, set out of alignment with the aperture  8  in the wall of the secondary tube  7 . 
         [0030]      FIG. 8  illustrates a preferred variant of the feature illustrated in  FIG. 7 , wherein a corresponding indent  15  and detent  16  are provided on the outside surface of the secondary tube  7  and the internal wall of the drainage tube  2  to allow rotational movement between the secondary tube  7  and the drainage tube  2 , but to resist relative axial movement there between. Again, such a configuration allows the drainage outlet  3  and aperture  7  to be reliably positioned either in or out of alignment. 
         [0031]    It will be appreciated that such a detent and indent mechanism could be arranged to provide a combination of rotational and axial movement by, for example, providing a helically disposed indent  15  that co-operates with a protruding detent  16 . 
         [0032]      FIG. 9  and  FIG. 10  illustrate respectively the distal and proximal ends of a catheter of the present invention. The intervening length of catheter is not illustrated, for clarity, but would typically have a length of between for example 30 cm to 1 m. Features common to those illustrated in earlier embodiments are correspondingly numbered. At the distal end of the catheter  1  illustrated in  FIG. 9 , the end of the secondary tube  7  is illustrated as being sealed with a plug  9 , but could be equally open, as illustrated in the embodiments of 
         [0033]      FIGS. 3 and 4  due to the arrangement at the proximal end, to be described. 
         [0034]      FIG. 10  illustrates the proximal end of the catheter  1  showing the exit of the installation lumen  10  to an installation port  17  adjacent the proximal end of the catheter. In this illustration, the port  17  is shown merely as the end of a tube, but could preferably and conveniently be provided with an appropriate connector such as a Luer connector, or in particularly preferred embodiments a self-sealing septum and/or a one-way valve (not illustrated). 
         [0035]      FIG. 10  illustrates that in this embodiment the secondary tube  7  is connected to the drainage tube  2  by means of a ratchet mechanism, generally indicated by  18 . The ratchet mechanism  18  has co-operating barbs  19  attached to elongate members  20  and connected to the secondary tube  7  via a pressure plate  21  connected to the outside of the secondary tube  7 . The drainage tube  2  is connected to the receiving portion  22  of the ratchet mechanism  18 . In use, the pressure plate  21  of the mechanism can be pushed toward the distal end of the catheter thereby moving the secondary tube  7  slidably within the drainage tube  2  and moving the tubes from the configuration shown in  FIG. 9  to that illustrated in  FIG. 5 , thereby closing the flow path between the distal and proximal ends of the catheter through the lumen of the secondary tube  7 . The ratchet mechanism  18  prevents the catheter being returned to its flow configuration, thereby preventing re-use of the device and hence preventing cross-infection that might result from re-use of the device. 
         [0036]      FIG. 11  illustrates in axial cross-sectional view, the distal end of a further embodiment of a catheter of the present invention. Again, features corresponding to those illustrated in other figures are numbered accordingly. In this embodiment, the catheter is further provided with a balloon  23  and  23 ′ adjacent an external wall of the drainage tube  2  near the distal end  4  of the catheter but proximal of the drainage opening  3  and preferably the installation opening  11 . The interior of the balloon  23  is connected through a balloon control channel  24  to a balloon control port at the proximal end of the catheter (not illustrated) allowing the balloon to be inflated from a first position  23  to an inflated position  23 ′ to anchor the catheter within the body cavity, for example at the neck of the urinary bladder. The balloon may subsequently be deflated to allow the catheter to be removed once drainage and/or installation of medicament have been carried out. 
         [0037]      FIGS. 12 and 13  illustrate the distal end of an alternative embodiment of a catheter of the present invention, generally indicated by  1 . In this embodiment, there is provided a drainage tube  2  again having a drainage opening  3  in its side wall. The drainage tube  2  is again sealed at its distal end  4  by means of a cap  5 . In this embodiment, the closure member is in the form of a plug  25  located within the lumen of the drainage tube  2  and so shaped and sized as to provide a slidable but generally fluid-tight seal between the outside surface of the plug  25  and the inner surface of the drainage tube  2 . The plug  25  is connected to a filament  26  that extends to a proximal end of the catheter and exiting the drainage tube  2  either at its end or, more preferably, through a side wall of the drainage tube  2 . In use, when it is required to seal the drainage outlet  3 , tension may be applied to the filament  26  to bring the plug  25  across the face of the drainage outlet  3  (or even further down the drainage tube) thereby sealing the flow path. The use of a filament, such as a length of nylon thread, renders the closure mechanism effectively irreversible due to the fact that the filament  25  is capable of transmitting forces in tension, but not in compression. 
         [0038]    In any embodiment described herein, it is particularly preferred that a fluid such as a light silicone grease be applied between the interior face of the drainage tube and the outer face of the closure member, either when the closure member is a plug  26  or a secondary tube  7 . The use of such a fluid serves two purposes: firstly to lubricate the relative sliding movement of the closure member and the drainage tube and, secondly to provide a more water tight seal there between. 
         [0039]    In use, the catheter would be initially configured such that there is an open passage between the drainage opening  3  and the drainage outlet port  27 . The catheter would be inserted into the body cavity, for example into the urinary bladder via the urethra, until fluid, such as urine, was seen to discharge from the drainage outlet port  27 , which could be conveniently connected to a collection bag via, e.g. a catheter tip connector. Once fluid was seen to discharge from the port, this would indicate that the catheter was in a suitable position within e.g. the bladder and, if one were provided, the location balloon  23  could be inflated to secure the catheter in place. It is particularly preferred and envisaged, however, that no such balloon  23  is provided, but that the proximal end of the catheter could merely be taped in to position on an extremity of a patient, for example on the patient&#39;s leg to secure the catheter in place whilst the drainage and/or installation of a drug were carried out. To aid such securement, a clip member may be provided into which the proximal end of the catheter can be secured and the clip fastened to the patient either with adhesive tape or some other releasable means. 
         [0040]    Once sufficient fluid (e.g. urine) had been drained from the body cavity, the closure member may be actuated to close the flow path between the drainage opening and the drainage outlet. At this stage, if medicament is to be administered, it can be introduced into the body cavity by injection through the installation port  17  at the proximal end of the catheter, to emerge at the installation outlet  11  via the installation lumen  10 . 
         [0041]    An example of a syringe and connector suitable for the administration of a medicament is illustrated in  FIGS. 14-16 . A standard syringe  140  is utilised to retain and deliver a measured volume through the syringe outlet  141 . The syringe outlet  141  is housed in, and connected to, the installation port  17  ( FIG. 10 ), by an adapted Luer slip connector. The adaptations described below prevent the connector from being used in conjunction with standard Luer fixtures. 
         [0042]    The connector comprises two main elements. The first element is an adapter  142  having, at a first end, a tapered recess  143  to receive the syringe outlet  141 . The outlet  141  and recess  143  connect via a push fit connection although additional bonding means can be included to provide a more secure connection. The second end of the adapter  142 , shown in the end view  FIG. 15   a  has recessed channels  144  and raised ribs  145 , which achieve the prevention of the fitment of the adapter  142  to a standard Luer as mentioned above. 
         [0043]    The adaptor  142  itself is seated in a one-way valve fitting  146  having at a first end a recess  147  of shape complementary to that of the channels  144  and ribs  145  to provide a secure fitting. The raised ribs  148  within the recess  147  prevent a standard Luer fitting from being inserted. The second end of the valve fitting  146  can be fitted to the installation port  17 . The one-way valve fitting  146  includes a spring  149  or other resilient means known in the art to bias the valve  146  to the closed position when no pressure is exerted on the fluid in the syringe  140 . The assembled syringe and connector, including the adapter  142  and valve fitting  146  is shown in  FIG. 16 . 
         [0044]    Once administration is complete, the locational balloon  23  (if present) may be deflated, and the catheter withdrawn from the body cavity for disposal.